Exhibit 10.42

                               AMENDMENT NO. 4 TO
             SECOND AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT

         This Amendment No. 4 to Second Amended and Restated Loan and Security
Agreement, dated as of June 29, 2001 (this "Amendment"), is by and among
GUARDIAN INTERNATIONAL, INC., a Florida corporation and successor-in-interest by
domestication under Florida law to Guardian International, Inc., a former Nevada
corporation ("Guardian"), the undersigned Borrowing Subsidiaries (Guardian and
the Borrowing Subsidiaries may be individually referred to herein as a
"Borrower", and collectively as "Borrowers") and HELLER FINANCIAL, INC., a
Delaware corporation ("Lender").

                              W I T N E S S E T H:

         WHEREAS, Borrowers and Lender are parties to that certain Second
Amended and Restated Loan and Security Agreement dated as of February 23, 1998
(as heretofore amended or otherwise modified, the "Loan Agreement"; capitalized
terms not otherwise defined herein have the definitions provided therefor in the
Loan Agreement);

         WHEREAS, Borrowers have requested that Lender amend the Loan Agreement
in certain respects; and

         WHEREAS, Lender has agreed to amend the Loan Agreement subject to the
terms and conditions hereof;

         NOW, THEREFORE, the parties hereto agree as follows:

         1. Amendments. Subject to the satisfaction of the conditions set forth
in Section 3 below, and in reliance on the representations, warranties,
covenants and other agreements contained herein, the Loan Agreement is hereby
amended as follows:

         (a)      Notwithstanding anything to the contrary set forth in
                  subsection 1.2 of the Loan Agreement, the parties hereto agree
                  that all financial statements and other relevant information
                  prepared by Borrowers and delivered to Lender, including
                  without limitation each Compliance Certificate, shall be
                  prepared to reflect the adoption by the Borrowers on or about
                  January 1, 2000 of SAB 101, an accounting policy regarding
                  revenue recognition.

         (b)      Subsection 2.1(A) of the Loan Agreement is hereby amended by
                  amending and restating the defined term "Borrowing Base" set
                  forth in clause (2) thereof as follows:

                  "Borrowing Base" means, as of any date of determination, an
                  amount equal to the aggregate MRI in respect of all Contracts
                  of Borrowers as of the last day of then most recently ended
                  month, multiplied by 21.
<PAGE>

         (c)      Subsection 6.1 of the Loan Agreement is hereby amended by
                  deleting the dollar amount "$500,000" set forth in clause (ii)
                  thereof, and by inserting the dollar amount "$600,000" in lieu
                  thereof.

         (d)      Subsection 6.4 of the Loan Agreement is hereby amended by (x)
                  amending clause (ii) therein to read: "(ii) 3.50:1.0 through
                  June 30, 2001" and (y) by inserting new clause (iii)
                  immediately following clause (ii) therein, which shall read as
                  follows: "(iii) 4.50:1.0 thereafter."

         (e)      Subsection 6.6 of the Loan Agreement is hereby amended by
                  deleting the clause "ten percent (10.0%)" set forth therein,
                  and by inserting in lieu thereof the clause "twelve percent
                  (12.0%)".

         (f)      For purposes of Sections 6.3, 6.4 and 6.5 of the Loan
                  Agreement, EBIDAT and Pro Forma EBIDAT as of any measurement
                  date shall be measured for the three month period most
                  recently preceding such measurement date for which financial
                  information is available, and shall be expressed on an
                  annualized basis.

         (g)      The defined term "Expiry Date" set forth in Annex A to the
                  Loan Agreement is hereby amended by deleting the date "June
                  30, 2002", and by inserting in lieu thereof the date "April 3,
                  2003."

         2. Conditions Precedent. The effectiveness of this Amendment is subject
to the satisfaction of the following conditions precedent (unless specifically
waived in writing by Lender):

         (a)      Borrowers shall have executed and delivered a copy of this
                  Amendment to Lender;

         (b)      Borrowers shall have paid to Lender a fee in respect of the
                  transactions contemplated hereunder in the amount of $125,000
                  (and by their execution hereof, Borrowers hereby authorize and
                  direct Lender to charge Borrowers' loan account for the full
                  amount of such fee);

         (c)      Borrowers shall have delivered to Lender copies of the
                  resolutions of the boards of directors of Borrowers with
                  respect to the transactions contemplated by this Amendment,
                  each certified as being true, complete and correct in all
                  respects by an officer of each Borrower;

         (d)      No Default or Event of Default shall have occurred and be
                  continuing;

         (e)      The warranties and representations of Borrowers contained in
                  this Amendment, the Loan Agreement, as amended hereby, and the
                  Loan Documents shall be true and correct in all material
                  respects as of the date hereof, with the same effect as though
                  made on such date.
<PAGE>

         3. Miscellaneous.

         (a)      Entire Agreement. This Amendment, including all schedules and
                  other documents attached hereto or incorporated by reference
                  herein, constitutes the entire agreement of the parties with
                  respect to the subject matter hereof and supercedes all other
                  understandings, oral or written, with respect to the subject
                  matter hereof.

         (b)      Captions. Section captions used in this Amendment are for
                  convenience only, and shall not affect the construction of
                  this Amendment.

         (c)      Costs and Expenses. As provided in Section 9.3 of the Loan
                  Agreement, Borrowers agree to pay on demand all reasonable
                  fees, costs and expenses incurred by Lender in connection with
                  the preparation, execution and delivery of this Amendment.

         (d)      Governing Law. This Amendment shall be a contract made under
                  and governed by the laws of the State of Illinois, without
                  regard to conflict of laws principles. Whenever possible each
                  provision of this Amendment shall be interpreted in such
                  manner as to be effective and valid under applicable law, but
                  if any provision of this Amendment shall be prohibited by or
                  invalid under such law, such provision shall be ineffective to
                  the extent of such prohibition or invalidity, without
                  invalidating the remainder of such provision or the remaining
                  provisions of this Amendment.

         (e)      Counterparts. This Amendment may be executed in any number of
                  counterparts and by the different parties on separate
                  counterparts, and each such counterpart shall be deemed to be
                  an original, but all such counterparts shall together
                  constitute but one and the same Amendment.

         (f)      Successors and Assigns. This Amendment shall be binding upon
                  and shall inure to the sole benefit of Borrowers and Lender
                  and their respective successors and assigns.

         (g)      References. Any reference to the Loan Agreement contained in
                  any notice, request, certificate, or other document executed
                  concurrently with or after the execution and delivery of this
                  Amendment shall be deemed to include this Amendment unless the
                  context shall otherwise require.

         (h)      Continued Effectiveness. Notwithstanding anything contained
                  herein, the terms of this Amendment are not intended to and do
                  not serve to effect a novation as to the Loan Agreement. The
                  parties hereto expressly do not intend to extinguish the Loan
                  Agreement. Instead, it is the express intention of the parties
                  hereto to reaffirm the indebtedness created under the Loan
                  Agreement which is evidenced by the Notes and secured by the
                  Collateral. The Loan Agreement as amended hereby and each of
                  the Loan Documents remain in full force and effect.



<PAGE>


         IN WITNESS WHEREOF, this Amendment has been duly executed as of the day
and year first above written.


                                                GUARDIAN INTERNATIONAL, INC.

                                                By:         /s/ DARIUS G. NEVIN
                                                         ----------------------
                                                           Darius G. Nevin
                                                Title:  Vice President



                                                MUTUAL CENTRAL ALARM SERVICES

                                                By:         /s/ DARIUS G. NEVIN
                                                         ----------------------
                                                           Darius G. Nevin
                                                Title:  Vice President



                                                HELLER FINANCIAL, INC.

                                                By:         /s/ SCOTT GAST
                                                         ----------------------
                                                             Scott Gast
                                                Title:  Vice President