<PAGE>   1
                                                                     Exhibit 4.3

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                           --------------------------
                               GUARANTY AGREEMENT
                           --------------------------

                           DATED AS OF MARCH 30, 2001

                                       RE:

                                   $35,000,000
                          SENIOR NOTES DUE MAY 31, 2003
                       ISSUED BY THE KROLL-O'GARA COMPANY
                     (FORMERLY KNOWN AS THE O'GARA COMPANY)



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<PAGE>   2




                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                               PAGE

<S>                                                                                                               <C>
1.       PRELIMINARY STATEMENTS.................................................................................  1

2.       GUARANTY AND OTHER RIGHTS AND UNDERTAKINGS.............................................................  2
         2.1      Guarantied Obligations........................................................................  2
         2.2      Waivers and Other Agreements..................................................................  3
         2.3      Nature of Guaranty............................................................................  3
         2.4      Obligations Absolute..........................................................................  4
         2.5      No Investigation by Noteholders...............................................................  5
         2.6      Indemnity.....................................................................................  5
         2.7      Subordination, Subrogation, Etc...............................................................  5
         2.8      Waiver........................................................................................  5
         2.9      Limitation on Guarantied Obligations..........................................................  6
         2.10     Marshaling....................................................................................  6
         2.11     Setoff, Counterclaim or Other Deductions......................................................  6
         2.12     No Election of Remedies by Noteholders........................................................  6
         2.13     Separate Action; Other Enforcement Rights.....................................................  6
         2.14     Noteholder Setoff.............................................................................  7
         2.15     Delay or Omission; No Waiver..................................................................  7
         2.16     Restoration of Rights and Remedies............................................................  7
         2.17     Cumulative Remedies...........................................................................  7

3.       INTERPRETATION OF THIS AGREEMENT.......................................................................  7
         3.1      Terms Defined.................................................................................  7
         3.2      Section Headings and Construction.............................................................  8

4.       WARRANTIES AND REPRESENTATIONS.........................................................................  9

5.       MISCELLANEOUS..........................................................................................  9
         5.1      Successors and Assigns........................................................................  9
         5.2      Severability..................................................................................  9
         5.3      Communications................................................................................  9
         5.4      Governing Law................................................................................. 10
         5.5      Benefits of Guaranty Restricted to Noteholders................................................ 10
         5.6      Survival of Representations and Warranties; Entire Agreement.................................. 10
         5.7      Amendment..................................................................................... 10
         5.8      Joinder Agreement............................................................................. 10
         5.9      Survival...................................................................................... 10
         5.10     Execution in Counterpart...................................................................... 11
</TABLE>

                                      i

<PAGE>   3

Annex 1  --       Addresses of Guarantors
Annex 2  --       Form of Joinder Agreement





                                      ii
<PAGE>   4





                               GUARANTY AGREEMENT

         GUARANTY AGREEMENT, dated as of March 30, 2001 (as may be amended,
restated or otherwise modified from time to time, this "AGREEMENT"), by and
among Corplex, Inc., a New York corporation, Inphoto Surveillance, Inc., an
Illinois corporation, Kroll Associates, Inc., a Delaware corporation, Kroll
Associates International Holdings, Inc., a Delaware corporation, Kroll
Background America, Inc., a Tennessee corporation, Kroll Buchler Phillips, Ltd.,
an English corporation, Kroll Environmental Enterprises, Inc., a Delaware
corporation, Kroll Holdings, Inc., a Delaware corporation, Kroll Information
Services, Inc., a Delaware corporation, Kroll Laboratory Specialists, Inc., a
Louisiana corporation, Kroll Lindquist Avey, Inc., a Texas corporation, Kroll
Schiff & Associates, Inc., a Texas corporation, Kroll-O'Gara Crisis Management
Group, Inc., a Virginia company, ITI Limited Partnership, a Texas limited
partnership, International Training, Incorporated, a Virginia corporation,
O'Gara-Hess & Eisenhardt Armoring Company, a Delaware corporation, O'Gara
Satellite Networks, Inc., a Delaware corporation, and O'Gara Security
International, Inc., a Delaware corporation, and each other Person that becomes
a party hereto from time to time by execution and delivery of a Joinder
Agreement (such Persons, including their respective successors and assigns,
herein referred to as the "GUARANTORS"), in favor of each of the Noteholders (as
such term is hereinafter defined).

1.       PRELIMINARY STATEMENTS

         1.1 Pursuant to the separate Amended and Restated Note Purchase
Agreements dated as of March 30, 2001 (collectively, as may be amended, restated
or otherwise modified from time to time, the "NOTE PURCHASE AGREEMENT"), between
The Kroll-O'Gara Company, formerly known as The O'Gara Company, (the "COMPANY"),
and each of the parties listed on Schedule A attached thereto, the Company has
agreed to amend and restate certain existing Note Purchase Agreements pursuant
to which the Company, among other things, issued its Senior Notes originally due
May 30, 2004, and as amended, due May 30, 2003, in the aggregate principal
amount of Thirty-Five Million Dollars ($35,000,000) (such Senior Notes as so
amended and as may be amended from time to time herein referred to as the
"NOTES").

         1.2 As contemplated by the terms of the Note Purchase Agreement, each
of the Guarantors has agreed to become a Guarantor hereunder.

         1.3 Each Guarantor will receive direct and indirect economic, financial
and other benefits from the transactions contemplated by the Note Purchase
Agreement and the Notes by the Company, and under this Agreement, and such
transactions are in the best interests of such Guarantor.

         1.4 All acts and proceedings required by law and by the constitutive
documents of each Guarantor necessary to constitute this Agreement a valid and
binding agreement for the uses and



<PAGE>   5

purposes set forth herein in accordance with its terms have been done and taken,
and the execution and delivery hereof have been in all respects duly authorized.

2.       GUARANTY AND OTHER RIGHTS AND UNDERTAKINGS

         2.1      GUARANTIED OBLIGATIONS.

                  (a) Each Guarantor, in consideration of the execution and
         delivery of the Note Purchase Agreement and other consideration, hereby
         irrevocably, unconditionally and absolutely guaranties, on a continuing
         basis, to each holder of Notes (each herein referred to as a
         "NOTEHOLDER") as and for such Guarantor's own debt:

                           (i) the prompt payment of the principal of the Notes
                  and any and all accrued and unpaid interest (including,
                  without limitation, interest which otherwise may cease to
                  accrue by operation of any insolvency law, rule, regulation or
                  interpretation thereof) on the Notes and all other obligations
                  of the Company to the Noteholders under the Note Purchase
                  Agreement when due, whether by mandatory or optional
                  prepayment, acceleration or otherwise, all in accordance with
                  the terms of the Note Purchase Agreement and the Notes,
                  including, without limitation, overdue interest,
                  indemnification payments and all reasonable costs and expenses
                  incurred by the Noteholders in connection with enforcing any
                  obligations of the Company under the Note Purchase Agreement
                  and the Notes, including, without limitation, the reasonable
                  fees and disbursements of Noteholders' special counsel,

                           (ii) the prompt and punctual performance and
                  observance of each and every term, covenant or agreement
                  contained in the Note Purchase Agreement and the Notes to be
                  performed or observed on the part of the Company, and

                           (iii) the prompt and complete payment, on demand, of
                  any and all reasonable costs and expenses incurred by the
                  Noteholders in connection with enforcing the obligations of
                  such Guarantor hereunder, including, without limitation, the
                  reasonable fees and disbursements of Noteholders' special
                  counsel.

         All of the obligations set forth in subsections (i), (ii) and (iii) of
         this Section 2.1 are referred to herein as the "GUARANTIED OBLIGATIONS"
         and the guaranty thereof contained herein is a primary, original and
         immediate obligation of each Guarantor and is an absolute,
         unconditional, continuing and irrevocable guaranty of payment and
         performance and shall remain in full force and effect until the full,
         final and indefeasible payment of the Guarantied Obligations.


<PAGE>   6

                  (b) If for any reason any duty, agreement or obligation of the
         Company contained in the Note Purchase Agreement shall not be performed
         or observed by the Company as provided therein, or if any amount
         payable under or in connection with the Note Purchase Agreement or the
         Notes shall not be paid in full when the same becomes due and payable,
         each Guarantor undertakes to perform or cause to be performed promptly
         each of such duties, agreements and obligations and to pay forthwith
         each such amount to the Noteholders regardless of any defense or setoff
         or counterclaim which the Company may have or assert, and regardless of
         any other condition or contingency.

         2.2      WAIVERS AND OTHER AGREEMENTS.

         Each Guarantor hereby unconditionally

                  (a) waives any requirement that the Noteholders, upon the
         occurrence of an Event of Default, first make demand upon, or seek to
         enforce remedies against, the Company before demanding payment under or
         seeking to enforce the obligations of such Guarantor under this
         Agreement,

                  (b) agrees that the obligations of such Guarantor under this
         Agreement will not be discharged except by complete performance of all
         obligations of the Company contained in the Note Purchase Agreement,
         the Notes and the other Financing Documents,

                  (c) agrees that the obligations of such Guarantor under this
         Agreement shall remain in full force and effect without regard to, and
         shall not be affected or impaired, without limitation, by any
         invalidity, irregularity or unenforceability in whole or in part of the
         Note Purchase Agreement, the Notes or any other Financing Document, or
         any limitation on the liability of any Guarantor under this Agreement,
         or any limitation on the method or terms of payment under the Note
         Purchase Agreement, the Notes or any other Financing Document which may
         at any time be caused or imposed in any manner whatsoever (including,
         without limitation, usury laws),

                  (d) waives diligence, presentment and protest with respect to,
         and any notice of default or dishonor in the payment of any amount at
         any time payable by the Company under or in connection with, the Note
         Purchase Agreement, the Notes or any other Financing Document, and
         further waives any requirement of notice of acceptance of, or other
         formality relating to, the obligations of such Guarantor under this
         Agreement, and

                  (e) agrees that to the extent the Company makes a payment or
         payments to any Noteholder, which payment or payments or any part
         thereof are subsequently invalidated, declared to be fraudulent or
         preferential, set aside or required, for any of the foregoing reasons
         or for any other reason, to be repaid or paid over to a custodian,
         trustee, receiver or any other party or officer under any bankruptcy,
         reorganization, arrangement, insolvency,


<PAGE>   7

         readjustment of debt, dissolution or liquidation law of any
         jurisdiction, state or federal law, or any common law or equitable
         cause, then to the extent of such payment or repayment, the obligation
         or part thereof intended to be satisfied shall be revived and continued
         in full force and effect as if said payment had not been made and each
         Guarantor shall be primarily liable for such obligation.

         2.3      NATURE OF GUARANTY.

         The obligations of each Guarantor under this Agreement constitute an
absolute and unconditional and irrevocable guaranty of payment and not a
guaranty of collection and are wholly independent of and in addition to other
rights and remedies of the Noteholders and are not contingent upon the pursuit
by the Noteholders of any such rights and remedies, such pursuit being hereby
waived by such Guarantor. Notwithstanding anything to the contrary set forth in
the Note Purchase Agreement, the Notes or any other Financing Document, the
obligations of each Guarantor under this Agreement are joint and several with
the obligations of each other Guarantor and any other guarantor of all or any
part of the Guarantied Obligations.

         2.4      OBLIGATIONS ABSOLUTE.

         The obligations, covenants, agreements and duties of each Guarantor
under this Agreement shall not be released, affected or impaired by any of the
following, whether or not undertaken with notice to or consent of such
Guarantor:

                  (a) any assignment or transfer, in whole or in part, of any
         Note although made without notice to or consent of such Guarantor, or

                  (b) any waiver by any Noteholder, or by any other Person, of
         the performance or observance by the Company of any of the agreements,
         covenants, terms or conditions contained in the Note Purchase Agreement
         or in any other Financing Document, or

                  (c) any indulgence in or the extension of the time for payment
         by the Company of any amounts payable under or in connection with the
         Note Purchase Agreement, the Notes or any other Financing Document, or
         of the time for performance by the Company of any other obligations
         under or arising out of the Note Purchase Agreement, the Notes or any
         other Financing Document, or the extension or renewal thereof, or

                  (d) the modification, amendment or waiver (whether material or
         otherwise) of any duty, agreement or obligation of the Company set
         forth in the Note Purchase Agreement, the Notes or any other Financing
         Document (the modification, amendment or waiver from time to time of
         the Note Purchase Agreement, the Notes and the other Financing
         Documents being expressly authorized without further notice to or
         consent of such Guarantor), or


<PAGE>   8

                  (e) the voluntary or involuntary liquidation, sale or other
         disposition of all or substantially all of the assets of the Company or
         any receivership, insolvency, bankruptcy, reorganization or other
         similar proceedings affecting the Company or any of its assets, or

                  (f) the merger or consolidation of the Company or any
         Guarantor with any other Person, or

                  (g) the release or discharge of the Company from the
         performance or observance of any agreement, covenant, term or condition
         contained in the Note Purchase Agreement, the Notes or any other
         Financing Document, by operation of law, or

                  (h) any other cause, whether similar or dissimilar to the
         foregoing, that would release, affect or impair the obligations,
         covenants, agreements or duties of any Guarantor under this Agreement.

         2.5      NO INVESTIGATION BY NOTEHOLDERS.

         Each Guarantor hereby waives unconditionally any obligation that, in
the absence of such provision, the Noteholders might otherwise have to
investigate or to assure that there has been compliance with the law of any
jurisdiction with respect to the Guarantied Obligations, recognizing that, to
save both time and expense, such Guarantor has requested that the Noteholders
not undertake such investigation. Each Guarantor hereby expressly confirms that
the obligations of such Guarantor hereunder shall remain in full force and
effect without regard to compliance or noncompliance with any such law and
irrespective of any investigation or knowledge of any such law by any
Noteholder.

         2.6      INDEMNITY.

         As a separate, additional and continuing obligation, each Guarantor
unconditionally and irrevocably undertakes and agrees with the Noteholders that,
should the Guarantied Obligations not be recoverable from such Guarantor under
Section 2.1 for any reason whatsoever (including, without limitation, by reason
of any provision of the Note Purchase Agreement or the Notes or any other
agreement or instrument executed in connection therewith being or becoming void,
unenforceable or otherwise invalid under any applicable law) then,
notwithstanding any knowledge thereof by any Noteholder at any time, such
Guarantor as sole, original and independent obligor, upon demand by any
Noteholder, will make payment of the Guarantied Obligations to such Noteholder
by way of a full indemnity in such currency and otherwise in such manner as is
provided in the Note Purchase Agreement and the Notes.


<PAGE>   9

         2.7      SUBORDINATION, SUBROGATION, ETC.

         Each Guarantor agrees that any present or future indebtedness,
obligations or liabilities of the Company to such Guarantor shall be fully
subordinate and junior in right and priority of payment to any present or future
indebtedness, obligations or liabilities of the Company to the Noteholders. Each
Guarantor waives any right of subrogation to the rights of the Noteholders
against the Company or any other Person obligated for payment of the Guarantied
Obligations and any right of reimbursement, contribution or indemnity whatsoever
(including, without limitation, any such right as against any other Guarantor)
arising or accruing out of any payment that such Guarantor may make pursuant to
this Agreement, and any right of recourse to security for the debts and
obligations of the Company, unless and until the entire amount of the Guarantied
Obligations shall have been paid in full.

         2.8      WAIVER.

         To the extent that it lawfully may, each Guarantor agrees that it will
not at any time insist upon or plead, or in any manner whatsoever claim or take
any benefit or advantage of, any applicable present or future stay, extension or
moratorium law, which may affect observance or performance of the provisions of
this Agreement, the Note Purchase Agreement, the Notes or any other Financing
Document; nor will it claim, take or insist upon any benefit or advantage of any
present or future law providing for the evaluation or appraisal of any security
for its obligations hereunder or the Company under the Note Purchase Agreement,
the Notes or any other Financing Document prior to any sale or sales thereof
which may be made under or by virtue of any instrument governing the same; nor
will it, after any such sale or sales, claim or exercise any right, under any
applicable law, to redeem any portion of such security so sold.

         2.9      LIMITATION ON GUARANTIED OBLIGATIONS.

         Notwithstanding anything in Section 2.1 or elsewhere in this Agreement
or any other Financing Document to the contrary, the obligations of each
Guarantor under this Agreement shall at each point in time be limited to an
aggregate amount equal to the greatest amount that would not result in such
obligations being subject to avoidance, or otherwise result in such obligations
being unenforceable, at such time under applicable law (including, without
limitation, to the extent, and only to the extent, applicable to any such
Guarantor, Section 548 of the Bankruptcy Code of the United States of America
and any comparable provisions of the law of any other jurisdiction, any capital
preservation law of any jurisdiction and any other law of any jurisdiction that
at such time limits the enforceability of the obligations of such Guarantor
under this Agreement).


<PAGE>   10

         2.10     MARSHALING.

         Neither any Noteholder nor any Person acting for the benefit of any
Noteholder shall be under any obligation to marshal any assets in favor of any
Guarantor or against or in payment of any or all of the Guarantied Obligations.

         2.11     SETOFF, COUNTERCLAIM OR OTHER DEDUCTIONS.

         Except as otherwise required by law, each payment by each Guarantor
shall be made without setoff, counterclaim or other deduction.

         2.12     NO ELECTION OF REMEDIES BY NOTEHOLDERS.

         No election to proceed in one form of action or proceeding, or against
any party, or on any obligation, shall constitute a waiver of such Noteholder's
right to proceed in any other form of action or proceeding or against other
parties unless such Noteholder has expressly waived such right in writing.
Specifically, but without limiting the generality of the foregoing, no action or
proceeding by any Noteholder against the Company or any Guarantor under any
document or instrument evidencing obligations of the Company or any Guarantor to
such Noteholder shall serve to diminish the liability of any Guarantor under
this Agreement, except to the extent that such Noteholder finally and
unconditionally shall have realized payment by such action or proceeding in
respect of the Guarantied Obligations.

         2.13     SEPARATE ACTION; OTHER ENFORCEMENT RIGHTS.

         Each of the rights and remedies granted under this Agreement to each
Noteholder in respect of the Notes held by such Noteholder may be exercised by
such Noteholder without notice by such Noteholder to, or the consent of or any
other action by, any other Noteholder. Each Noteholder may proceed to protect
and enforce this Agreement by suit or suits or proceedings in equity, at law or
in bankruptcy, and whether for the specific performance of any covenant or
agreement contained herein or in execution or aid of any power herein granted or
for the recovery of judgment for the obligations hereby guarantied or for the
enforcement of any other proper, legal or equitable remedy available under
applicable law.

         2.14     NOTEHOLDER SETOFF.

         Each Noteholder shall have, to the fullest extent permitted by law and
this Agreement, a right of set-off against any and all credits and any and all
other property of each Guarantor now or at any time whatsoever, with or in the
possession of such Noteholder, or anyone acting for such Noteholder, to ensure
the full performance of any and all obligations of each Guarantor hereunder.


<PAGE>   11

         2.15     DELAY OR OMISSION; NO WAIVER.

         No course of dealing on the part of any Noteholder and no delay or
failure on the part of any such Person to exercise any right hereunder shall
impair such right or operate as a waiver of such right or otherwise prejudice
such Person's rights, powers and remedies hereunder. Every right and remedy
given by this Agreement or by law to any Noteholder may be exercised from time
to time as often as may be deemed expedient by such Person.

         2.16     RESTORATION OF RIGHTS AND REMEDIES.

         If any Noteholder shall have instituted any proceeding to enforce any
right or remedy under this Agreement or under any Note held by such Noteholder,
and such proceeding shall have been dismissed, discontinued or abandoned for any
reason, or shall have been determined adversely to such Noteholder, then and in
every such case each such Noteholder, the Company and each Guarantor shall,
except as may be limited or affected by any determination (including, without
limitation, any determination in connection with any such dismissal) in such
proceeding, be restored severally and respectively to its respective former
positions hereunder and thereunder, and thereafter, subject as aforesaid, the
rights and remedies of such Noteholders shall continue as though no such
proceeding had been instituted.

         2.17     CUMULATIVE REMEDIES.

         No remedy under this Agreement, the Note Purchase Agreement, the Notes
or any other Financing Document is intended to be exclusive of any other remedy,
but each and every remedy shall be cumulative and in addition to any and every
other remedy given pursuant to this Agreement, the Note Purchase Agreement, the
Notes or any other Financing Document.

3.       INTERPRETATION OF THIS AGREEMENT

         3.1      TERMS DEFINED.

         As used in this Agreement, the capitalized terms have the meaning
specified in the Note Purchase Agreement unless otherwise specified below or set
forth in the section of this Agreement referred to immediately following such
term (such definitions, unless otherwise expressly provided, to be equally
applicable to both the singular and plural forms of the terms defined):

         AGREEMENT, THIS -- has the meaning assigned to such term in the first
paragraph hereof.

         COMPANY -- is defined in Section 1.1.

         GUARANTIED OBLIGATIONS -- is defined in Section 2.1.


<PAGE>   12

         GUARANTORS -- has the meaning assigned to such term in the first
paragraph hereof.

         NOTE PURCHASE AGREEMENT -- is defined in Section 1.1.

         NOTEHOLDER -- is defined in Section 2.1.

         NOTES -- is defined in Section 1.1.

         3.2      SECTION HEADINGS AND CONSTRUCTION.

                  (a) SECTION HEADINGS, ETC. The titles of the Sections appear
         as a matter of convenience only, do not constitute a part hereof and
         shall not affect the construction hereof. The words "herein," "hereof,"
         "hereunder" and "hereto" refer to this Agreement as a whole and not to
         any particular Section or other subdivision.

                  (b) CONSTRUCTION. Each covenant contained herein shall be
         construed (absent express provision to the contrary) as being
         independent of each other covenant contained herein, so that compliance
         with any one covenant shall not (absent such an express contrary
         provision) be deemed to excuse compliance with any other covenant.
         Where any provision herein refers to action to be taken by any Person,
         or which such Person is prohibited from taking, such provision shall be
         applicable whether such action is taken directly or indirectly by such
         Person.

4.       WARRANTIES AND REPRESENTATIONS

         Each Guarantor warrants and represents, as of the date such Guarantor
becomes a Guarantor hereunder, that each of the warranties and representations
made by the Company in Section 4 of the Note Purchase Agreement with respect to
Subsidiaries or the Guarantors generally are true with respect to such Guarantor
on the date that such Guarantor becomes a Guarantor, with the same effect as
though such warranties and representations were made on and as of such date
rather than on and as of the date of this Agreement.

5.       MISCELLANEOUS

         5.1      SUCCESSORS AND ASSIGNS.

                  (a) All covenants and other agreements contained in this
         Agreement by or on behalf of any of the parties hereto shall bind and
         inure to the benefit of their respective successors and assigns
         (including, without limitation, any subsequent holder of a Note)
         whether so expressed or not.

                  (b) Each Guarantor agrees to take such action as may be
         reasonably requested by any Noteholder to confirm such Guarantor's
         guaranty of the Guarantied Obligations in


<PAGE>   13

         connection with the transfer of the Notes of such Noteholder.

         5.2      SEVERABILITY.

         Any provision of this Agreement that is prohibited or unenforceable in
any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of
such prohibition or unenforceability without invalidating the remaining
provisions hereof, and any such prohibition or unenforceability in any
jurisdiction shall (to the full extent permitted by law) not invalidate or
render unenforceable such provision in any other jurisdiction.

         5.3      COMMUNICATIONS.

         All communications hereunder shall be in writing, shall be delivered in
the manner required by the Note Purchase Agreement, and shall be addressed, if
to any Guarantor, at the applicable address set forth on ANNEX 1 hereto, and if
to any of the Noteholders:

                  (a) if such Noteholder is a holder of the Notes on the
         Restatement Date, at the address for such Noteholder set forth on
         Schedule A to the Note Purchase Agreement, and further including any
         parties referred to on such Schedule A which are required to receive
         notices in addition to such Noteholder, and

                  (b) if such Noteholder is not a holder of the Notes on the
         Restatement Date, at the address for such Noteholder set forth in the
         register for the registration and transfer of Notes maintained pursuant
         to Section 11.1 of the Note Purchase Agreement,

or to any such party at such other address as such party may designate by notice
duly given in accordance with this Section 5.3.

Notices shall be deemed given only when actually received.

         5.4      GOVERNING LAW.

         THIS AGREEMENT SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH, AND
THE RIGHTS OF THE PARTIES SHALL BE GOVERNED BY, THE LAW OF THE STATE OF NEW YORK
EXCLUDING CHOICE-OF-LAW PRINCIPLES OF THE LAW OF SUCH STATE THAT WOULD REQUIRE
THE APPLICATION OF THE LAWS OF A JURISDICTION OTHER THAN SUCH STATE.

         5.5      BENEFITS OF GUARANTY RESTRICTED TO NOTEHOLDERS.

         Nothing express or implied in this Agreement is intended or shall be
construed to give to any Person other than the Guarantors and the Noteholders
any legal or equitable right, remedy or claim under or in respect hereof or any
covenant, condition or provision therein or herein contained,


<PAGE>   14

and all such covenants, conditions and provisions are and shall be held to be
for the sole and exclusive benefit of the Guarantors and the Noteholders.

         5.6      SURVIVAL OF REPRESENTATIONS AND WARRANTIES; ENTIRE AGREEMENT.

         All representations and warranties contained herein or made in writing
by any Guarantor in connection herewith shall survive the execution and delivery
of this Agreement.

         5.7      AMENDMENT.

         This Agreement may be amended, and the observance of any term hereof
may be waived (either retroactively or prospectively), with (and only with) the
written consent of each Guarantor and the Required Holders, except that no
amendment or waiver of any of the provisions of Section 2, or any defined term
as it is used therein, will be effective unless consented to by each Guarantor
and each Noteholder in writing; provided that this Agreement may, in the manner
specified in Section 5.8, be amended to add one or more new Guarantors hereunder
without the consent of any other Guarantor or any holder of Notes.

         5.8      JOINDER AGREEMENT.

         Upon execution and delivery by any Person of a counterpart of a Joinder
Agreement substantially in the form attached to this Agreement as ANNEX 2, this
Agreement shall for all purposes, without further action, be deemed to have been
amended to add such Person as a Guarantor hereunder with the same effect as if
such Person had been an original party hereto.

         5.9      SURVIVAL.

         So long as the Guarantied Obligations and all payment obligations of
each Guarantor hereunder shall not have been fully and finally performed and
indefeasibly paid, the obligations of each Guarantor hereunder shall survive the
transfer and payment of any Note and the payment in full of all the Notes.

         5.10     EXECUTION IN COUNTERPART.

         This Agreement may be executed in any number of counterparts, each of
which shall be an original but all of which together shall constitute one
instrument. Each counterpart may consist of a number of copies hereof, each
signed by less than all, but together signed by all, of the parties hereto.

      [REMAINDER OF PAGE INTENTIONALLY BLANK. NEXT PAGE IS SIGNATURE PAGE.]


<PAGE>   15







         IN WITNESS WHEREOF, each Guarantor has caused this Agreement to be
executed on its behalf by one of its duly authorized officers.

                                     CORPLEX, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     INPHOTO SURVEILLANCE, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL ASSOCIATES, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL ASSOCIATES INTERNATIONAL
                                     HOLDINGS, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL BACKGROUND AMERICA, INC.

                                     By__________________________________
                                     Name:
                                     Title:


<PAGE>   16

                                     KROLL ENVIRONMENTAL ENTERPRISES, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL HOLDINGS, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL INFORMATION SERVICES, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL LABORATORY SPECIALISTS, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL LINDQUIST AVEY, INC.

                                     By__________________________________
                                     Name:
                                     Title:


<PAGE>   17


                                     KROLL SCHIFF & ASSOCIATES, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     O'GARA-HESS & EISENHARDT ARMORING COMPANY

                                     By__________________________________
                                     Name:
                                     Title:

                                     O'GARA SATELLITE NETWORKS, INC.

                                     By__________________________________
                                     Name:
                                     Title:

                                     O'GARA SECURITY INTERNATIONAL, INC.

                                     By__________________________________
                                     Name:
                                     Title:


<PAGE>   18


                                     KROLL-O'GARA CRISIS MANAGEMENT GROUP, INC.


                                     By__________________________________
                                     Name:
                                     Title:

                                     ITI LIMITED PARTNERSHIP

                                     By__________________________________
                                     Name:
                                     Title:

                                     INTERNATIONAL TRAINING, INCORPORATED

                                     By__________________________________
                                     Name:
                                     Title:

                                     KROLL BUCHLER PHILLIPS, LTD.

                                     By__________________________________
                                     Name:
                                     Title: