Document:

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                                                                    Exhibit 10.1

                                 March 28, 2005

CONFIDENTIAL

Mr. William R. Thistle
c/o Psychemedics Corporation
125 Nagog Park, Suite 200
Acton, MA  01720

Dear Bill:

      This letter sets forth the agreements we have made regarding your
employment with Psychemedics Corporation (the "Company").

      1.    If after the effective date hereof, your employment is terminated by
            the Company without "Cause" (as defined in paragraph 13 below), or
            you voluntarily terminate your employment for "Good Reason" (as
            defined in paragraph 13 below), in either case at the time of, or
            within twelve (12) months following, a "Change of Control of the
            Company" (as defined in paragraph 13 below), then you will continue
            to be paid monthly an amount equal to your average monthly
            compensation for the twelve full months preceding the date of such
            termination ("Termination Pay") for a period of twelve (12) months
            from the date of such termination. For purposes of the foregoing
            sentence, average monthly compensation shall be determined with
            reference to the aggregate base salary and bonus compensation earned
            by you during such period, including any bonus compensation accrued
            for such period or any portion of such period but not paid as of the
            date of such termination). Your Termination Pay will be subject to
            normal deductions for taxes, benefit plan contributions, other
            payroll deductions and any amount due the Company as a result of
            cash advances. The Company agrees to continue to make health
            insurance available to you under such health insurance plan as the
            Company has in effect for so long as you are receiving Termination
            Pay and so long as you contribute such portion of the premiums for
            such insurance as is required of employees under such plan. You
            agree, however, that if you obtain health insurance coverage through
            another employer while you are eligible to receive health insurance
            under this Agreement, the Company shall no longer be required to
            make health insurance available to you under this Agreement. You
            agree to give the Company at least fourteen (14) days prior written
            notice of the termination of your employment in the event of your
            voluntary termination without Good Reason. You shall not

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            be entitled to Termination Pay as a result of termination by reason
            of your death or "Disability" (as defined in paragraph 13 below)
            following a Change of Control of the Company.

      2.    Notwithstanding any other provision of this Agreement, the
            Termination Pay contemplated to be paid to you under certain
            circumstances set forth in this Agreement shall only be paid in
            consideration of the execution and delivery by you of a release
            reasonably satisfactory to the Company waiving all claims you, your
            heirs, or legal representatives have or may have against the Company
            or any of its shareholders, officers, directors, employees or agents
            with respect to your employment or the termination thereof, or any
            other claim.

      3.    You acknowledge that, as the Company's Senior Vice President and
            General Counsel, you are in possession of specialized information
            concerning the total operations, conduct, management, and strategy
            of the Company, as well as proprietary information concerning the
            Company's products and services and that the applicability of your
            knowledge of these matters is applicable to all geographic areas in
            which the Company does business. You further acknowledge that the
            Company has a legitimate business interest in protecting its hair
            testing business from unfair competition.

      4.    You shall not, without the prior and express written approval of the
            Company, either during or subsequent to the term of your employment,
            disclose or use or enable another to disclose or use any secret,
            private or confidential information, trade secret or other
            proprietary knowledge of the Company, or its subsidiaries,
            divisions, employees or agents. Upon termination of your employment
            with the Company, you shall deliver to the Company all equipment,
            records and copies of records, notes, data, memoranda, prototypes,
            designs, customer lists and other information which is embodied in
            physical media and documents belonging to the Company which are then
            in your possession. You agree that all such information and
            documents shall be the property of the Company and that the
            obligations set forth in this paragraph shall survive termination of
            your employment.

      5.    You agree that, if you or the Company shall terminate your
            employment in such a manner as to entitle you to Termination Pay
            under paragraph 1, above, you shall not, for so long as you are
            entitled to receive such Termination Pay:

            (a) directly or indirectly own, manage, operate or control, or
            participate in the ownership, management, operation or control of,
            or become associated in any capacity with any business enterprise,
            firm, corporation or company related to the field of testing for the
            detection of drug use,

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            which is in competition with the business of the Company, or
            directly or indirectly accept employment with or render services on
            behalf of a competitor of the Company, or any other third party, in
            any capacity which may reasonably be considered to be useful to the
            competitor or such other third party to become a competitor, without
            receiving the Company's prior written approval; or

            (b) induce or attempt to induce any employee, officer, consultant,
            or agent of the Company to leave the employ thereof or in any way
            interfere with the relationship between the Company and any
            employee, officer, consultant, or agent thereof; hire directly or
            through another entity any person who was an employee of the Company
            at any time during the six (6) months prior to the date such person
            is to be so hired; or induce or attempt to induce any customer,
            client, supplier, licensee, or other business relation of the
            Company to cease doing business with the Company or in any way
            interfere with the relationship between any such customer, client,
            supplier, licensee, or business relation and the Company (including,
            without limitation, making any negative statements or communications
            concerning the Company).

      6.    You agree that your obligations under paragraphs 4 and 5 are
            special, unique, and extraordinary and that any breach by you of
            such obligations shall be deemed material, and shall be deemed to
            cause irreparable injury not properly compensable by damages in an
            action at law, and the rights and remedies of the Company under
            paragraphs 4 and 5 may, therefore, be enforced both at law and in
            equity, by injunction or otherwise. For purposes of paragraphs 4 and
            5, the term "Company" shall include any and all subsidiaries or
            divisions of the Company.

      7.    The Company's obligations under paragraph 1 of this Agreement shall
            expire five (5) years from the date hereof, unless the parties agree
            in writing to the renewal of the provisions of such paragraph. All
            of the remaining provisions of this Agreement shall remain in full
            force and effect during the term of your employment and thereafter
            in accordance with their terms.

      8.    If at any time a controversy between you and the Company arises as
            to the meaning or operation of this Agreement, such controversy
            shall be submitted to arbitration by either party in Boston,
            Massachusetts, before an arbitrator to be named by the President of
            the Boston Branch of the American Arbitration Association, provided
            however, that the Company shall also have the rights set forth in
            paragraph 6 above. Such arbitration proceedings shall be conducted
            in accordance with the rules and procedures then in effect of the
            American Arbitration Association. The decision of the arbitrator
            shall be binding upon the parties and judgment on any award made by
            the arbitrator may be entered in any court having

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            jurisdiction thereof. The costs of the arbitrator shall be borne
            equally by you and the Company. Each party will bear his or its own
            legal costs.

      9.    This Agreement shall be governed by and interpreted in accordance
            with the laws of the Commonwealth of Massachusetts without reference
            to principles of conflict of laws.

      10.   This Agreement contains the entire agreement of the parties in
            respect of this transaction and supersedes any prior agreement or
            understanding relating to your employment by the Company. No
            amendment or modification of any provision of this Agreement will be
            valid unless in writing signed by both parties. Any waiver must be
            in writing and signed by you or an authorized officer of the
            Company, as the case may be.

      11.   This Agreement shall be binding upon and inure to the benefit of:
            (a) the Company, and any successors or assigns of the Company,
            whether by way of a merger or consolidation, or liquidation of the
            Company, or by way of the Company selling all or substantially all
            of the assets and business of the Company to a successor entity;
            and, subject to the Company's right to terminate your employment at
            any time, the Company agrees to require any successor entity to
            expressly assume or unconditionally guarantee the Company's
            obligations under this Agreement (unless such obligations are
            assumed by operation of law); and (b) you and your heirs, executors
            and administrators.

      12.   Any notice or other communication required hereunder shall be in
            writing, shall be deemed to have been given and received when
            delivered in person, or, if mailed, shall be deemed to have been
            given when deposited in the United States mail, first class,
            registered or certified, return receipt requested, with proper
            postage prepaid, and shall be deemed to have been received on the
            third business day thereafter, and shall be addressed as follows:

            If to the Company, addressed to:

                        Psychemedics Corporation
                        125 Nagog Park, Suite 200
                        Acton, MA  01720
                        Attn:  President

            If to you, addressed to:

                        William R. Thistle
                        Psychemedics Corporation
                        125 Nagog Park, Suite 200
                        Acton, MA  01720

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            or such other address as to which any party hereto may have notified
            the other in writing.

      13.   Definitions.

            (a) "Cause" shall mean: (i) theft or embezzlement, or attempted
            theft or embezzlement, by you of money or property of the Company,
            your perpetration or attempted perpetration of fraud, or your
            participation in a fraud or attempted fraud upon the Company; (ii)
            your unauthorized appropriation of, or attempt to misappropriate,
            any tangible or intangible assets or property of the Company, or
            your appropriation of, or attempt to appropriate, a business
            opportunity of the Company, including but not limited to attempting
            to secure or securing any profit for yourself or any of your family
            members or personal associates in connection with any transaction
            entered into on behalf of the Company; (iii) any act or acts of
            disloyalty, misconduct, or moral turpitude by you, including but not
            limited to violation of the Company's sexual harassment or
            non-harassment policy, any of which the Board of Directors of the
            Company determines in good faith has been or is likely to be
            materially injurious to the interest, property, operations,
            business, or reputation of the Company, or its directors, employees
            or shareholders; (iv) any act or omission constituting gross
            negligence in connection with the performance of your duties on
            behalf of the Company which is materially injurious to the interest,
            property, operations, business, or reputation of the Company; (v)
            your conviction of a crime other than minor traffic violations or
            other similar minor offenses (including pleading guilty or entering
            a plea of no contest), or your indictment for a felony or its
            equivalent, or your being charged with a violent crime, a crime
            involving moral turpitude, or any other crime for which imprisonment
            is a possible punishment; (vi) your willful refusal or material
            failure (other than by reason of Disability) to carry out reasonable
            and lawful instructions and directives from the Board of Directors
            and your failure to cure or correct such refusal or failure within
            ten (10) days after receiving written notice from the Board of
            Directors describing such refusal or failure; or (vii) the material
            breach by you of your obligations under paragraphs 4 or 5 hereof or
            under any other confidentiality, non-compete, non-solicitation,
            non-disparagement or similar agreement with the Company.

            (b) "Change in Control of the Company" shall mean

                  (i) the number of shares of Common Stock directly or
                  indirectly beneficially owned, as defined in Rule 13d-3 under
                  the Securities Exchange Act of 1934 (the "Exchange Act"), by
                  the Buyers and Permitted Assignees (as defined in the
                  Securities Purchase Agreement dated May 15, 1989, as amended
                  from time to time, by

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                  and among the Company, A. Clinton Allen, H. Wayne Huizenga,
                  Donald F. Flynn, Beverly L. Flynn, Patricia A. Flynn as
                  Trustee, MW Partners and Psychemedics Investments, Inc. as
                  nominee), and the spouses or children of any of the foregoing,
                  and trusts for the benefit of any of the foregoing or for the
                  benefit of any partner or former partner in MW Partners
                  (collectively the "Principal 1989 Shareholders"), in the
                  aggregate, is less than the aggregate number of shares of
                  Common Stock directly or indirectly beneficially owned (as
                  defined above) at any time by any other person or group (as
                  defined in Section 13(d) of the Exchange Act); or

                  (ii) the consummation of a reorganization, merger or
                  consolidation or sale or disposition of all or substantially
                  all of the assets of the Company (a "Business Combination"),
                  unless, in each case following such Business Combination, (A)
                  all or substantially all of the individuals and entities who
                  were the beneficial owners of the Common Stock of the Company
                  immediately before the consummation of such Business
                  Combination beneficially own, directly or indirectly, more
                  than 50% of, respectively, the then outstanding shares of
                  common stock and the combined voting power of the then
                  outstanding voting securities entitled to vote generally in
                  the election of directors, as the case may be, of the
                  corporation resulting from such Business Combination
                  (including, without limitation, a corporation that as a result
                  of the transaction owns the Company or all or substantially
                  all of the assets of the Company either directly or indirectly
                  through one or more subsidiaries) in substantially the same
                  proportions as their ownership, immediately prior to such
                  Business Combination, of the Common Stock of the Company; and
                  (B) no person or group (as defined in Section 13(d) of the
                  Exchange Act) of the Company or the corporation resulting from
                  the Business Combination) beneficially owns, directly or
                  indirectly, a number of the then outstanding shares of the
                  common stock of the corporation resulting from the Business
                  Combination or the combined voting power of the then
                  outstanding voting securities of the corporation greater than
                  the number of such shares owned by the Principal 1989
                  Shareholders; or

                  (iii) Individuals who, as of the date of this Agreement,
                  constitute the Board of Directors of the Company (the
                  "Incumbent Board") cease for any reason to constitute at least
                  a majority of the Board of Directors of the Company, provided,
                  however, that any individual's becoming a director after the
                  date of this Agreement whose election, or nomination for
                  election by the stockholders of the Company, was approved by a
                  vote of at least a majority of

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                  the directors then comprising the Incumbent Board will be
                  considered as though the individual were a member of the
                  Incumbent Board, but excluding, for this purpose, any
                  individual whose initial assumption of office occurs as a
                  result of an actual or threatened election contest with
                  respect to the election or removal of directors or other
                  actual or threatened solicitation of proxies or consents by or
                  on behalf of a Person other than the Board.

            (c) "Disability" shall mean your inability because of physical or
            mental incapacity to perform your usual duties at the Company for a
            period of one hundred eighty (180) days in any consecutive twelve
            (12) month period.

            (d) "Good Reason" shall mean: (i) reduction in your base salary
            below $222,500 or such higher base salary as is in effect
            immediately prior to such reduction; or (ii) a material decrease in
            your duties or responsibilities.

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      If this letter correctly sets forth our understanding and agreement,
please indicate your acceptance by signing both copies of this letter and
returning one copy.

                                           Very truly yours,

                                           PSYCHEMEDICS CORPORATION

                                           By:/s/ Raymond C. Kubacki, Jr.
                                             -----------------------------------
                                              Raymond C. Kubacki, Jr., President

Agreed to: March 28, 2005

/s/ William R. Thistle
----------------------------
William R. Thistle<PAGE>
                                                                     Exhibit 4.2

NUMBER                         [AMICAS, INC. LOGO]                        SHARES
A
                                  AMICAS, INC.
              INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE
PAR VALUE $.001                                                CUSIP 001712 10 8
                                             SEE REVERSE FOR CERTAIN DEFINITIONS

THIS certifies that

is the owner of

      FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK OF AMICAS, INC.
transferable only on the books of the Corporation by the holder hereof in
person or by duly authorized Attorney upon surrender of this Certificate
properly endorsed. This Certificate and the shares represented hereby are
issued and shall be held subject to all of the provisions of the Certificate of
Incorporation of the Corporation, By-Laws and all Amendments thereto, to all of
which the holder, by acceptance hereof assents.
          This Certificate is not valid unless countersigned and registered by
          the Transfer Agent and Registrar.
          WITNESS the facsimile seal of the Corporation and the facsimile
          signatures of its duly authorized officers.

Dated:
                       [AMICAS, INC. SEAL 1996 DELAWARE]

[Illegible Sig]                                                  [Illegible Sig]
Chief Financial Officer                    President and Chief Executive Officer

                                Countersigned and Registered:
                                             STOCKTRANS, INC.
                                             44 West Lancaster Ave.
                                             Ardmore, PA 19003

                                                                  Transfer Agent
                                                                  and Registrar,

                                By
                                                            Authorized Signature
<PAGE>
                                  AMICAS, INC.

     The Corporation will furnish without charge to each stockholder who so
requests the powers, designations, preferences and relative, participating,
optional or other special rights of each class of stock or series thereof of
the Corporation, and the qualifications, limitations or restrictions of such
preferences and/or rights.

     The following abbreviations, when used in the inscription on the face of
this Certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM - as tenants in common        UNIF GIFT MIN ACT - ______Custodian_______
                                                          (Cust)         (Minor)
TEN ENT - as tenants by the entireties             under Uniform Gifts to Minors

JT TEN - as joint tenants with right                      Act __________________
         of survivorship and not as                                (State)
         tenants in common

    Additional abbreviations may also be used though not in the above list.

     For value received, ___________ hereby sell, assign and transfer unto
     PLEASE INSERT SOCIAL SECURITY OR OTHER
         IDENTIFYING NUMBER OF ASSIGNEE

     ___________________________________________________________________________

     ___________________________________________________________________________
   (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OR ASSIGNEE)
     ___________________________________________________________________________

     ___________________________________________________________________________

     ____________________________________________________________________ shares

     of the common stock represented by the within Certificate and do hereby

     irrevocably constitute and appoint ________________________________________

     __________________________________________________________________ Attorney

     to transfer the said stock on the books of the within named Corporation

     with full power of substitution in the premises.

Dated: _____________________

                                        ________________________________________
                              NOTICE:   THE SIGNATURE TO THIS ASSIGNMENT MUST
                                        CORRESPOND WITH THE NAME AS WRITTEN UPON
                                        THE FACE OF THE CERTIFICATE IN EVERY
                                        PARTICULAR, WITHOUT ALTERATION OR
                                        ENLARGEMENT, OR ANY CHANGE WHATSOEVER.

Signature(s) Guaranteed:

_______________________________________________
THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN
ELIGIBLE GUARANTOR INSTITUTION (BANKS,
STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS
AND CREDIT UNIONS WITH MEMBERSHIP IN AN
APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM),
PURSUANT TO S.E.C. RULE 17Ad-15.

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