EXHIBIT 4.2


                     AMENDMENT TO STOCK PURCHASE AGREEMENT


     THIS AMENDMENT entered into as of _______________________, 1999, by and
among Borg-Warner Security Corporation, a Delaware corporation (the "Company"),
and each of the entities set forth under the heading "Sellers" on the signature
pages hereto (each, a "Seller" and collectively, the "Sellers"), hereby amends
the Stock Purchase Agreement (the "Stock Purchase Agreement") entered into as
of April 19, 1999, by and among the Company and each of the Sellers. The
Company and the Sellers are referred to collectively herein as the "Parties."

     WHEREAS, under the Stock Purchase Agreement, the Company agreed to
purchase an aggregate of 4,350,000 shares of common stock of the Company (the
"Common Stock"), and agreed to provide certain registration rights to the
Sellers and certain other Merrill Lynch Holders (as defined in the Registration
Rights Agreement dated as of July 27, 1987 by and among the Company and the
other parties thereto (the "Registration Rights Agreement")) with respect to
their remaining shares of Common Stock.

     WHEREAS, this Amendment hereby amends the registration rights provisions
set forth in the Stock Purchase Agreement.

     NOW, THEREFORE, in consideration of the premises and the actual promises
herein made, and in consideration of the representations, warranties, and
covenants herein contained, the Parties agree as follows:

     Section 1. Amendment. Section 5(b) of the Stock Purchase Agreement is
hereby amended and restated in its entirety to read as follows:

     (a) Registration Statement. The Parties hereby acknowledge that pursuant
to Section 3 of the Registration Rights Agreement, the Merrill Lynch Holders
have made a request that the Company effect a registration under the Securities
Act of 1933, as amended (the "Securities Act"), to register 5,850,000 shares of
Common Stock constituting Registrable Securities (as such term is defined in
the Registration Rights Agreement), and on May 21, 1999 the Company filed an
S-3 Resale Registration Statement with the Securities and Exchange Commission
(the "SEC") pursuant to Rule 415 under the Securities Act (the "Shelf
Registration"). The Shelf Registration Statement became effective with the SEC
on June 8, 1999.

     (b) Except as otherwise provided herein, the Company shall use all
reasonable efforts to keep the Shelf Registration Statement continuously
effective until the earlier of (A) such time as all of the remaining
Registrable Securities subject to the Shelf Registration Statement have been
disposed of or are no longer Registrable Securities (as defined in the
Registration Rights Agreement), or (B) 365 days after the date on which such
Shelf Registration Statement becomes effective.

     (c) If the continued effectiveness of the Shelf Registration Statement at
any time would require the Company to make an Adverse Disclosure, then the
Company may, upon giving prompt written notice of such action to the Merrill
Lynch Holders, delay filing the Shelf Registration Statement or suspend use of
the Shelf Registration Statement (in either case, a






"Suspension"); provided, however, the Company shall not be permitted to
exercise a Suspension (i) more than three times during any twelve (12) month
period, or (ii) for a period exceeding ninety (90) days on any one occasion, or
(iii) for an aggregate period exceeding one hundred fifty (150) days in the
twelve (12) month period during which the Shelf Registration Statement is to be
effective. In the case of a Suspension, the notice required above shall request
the Merrill Lynch Holders to suspend any sale or purchase, or offer to sell or
purchase of the Registrable Shares subject to the Shelf Registration Statement,
and to suspend use of the Prospectus related to the Shelf Registration
Statement in connection with any such sale or purchase or offer to sell or
purchase. The Company shall immediately notify the Merrill Lynch Holders upon
the termination of any Suspension, amend or supplement the Prospectus, if
necessary, so it does not contain any untrue statement or omission therein and
furnish to the Merrill Lynch Holders such numbers of copies of the Prospectus
as so amended or supplemented as the Merrill Lynch Holders may reasonably
request. "Adverse Disclosure" means the public disclosure of material
non-public information relating to a significant transaction, which disclosure
(i) would be required to be made in any registration statement filed with the
SEC by the Company so that such registration statement would not be materially
misleading; (ii) would not be required to be made at such time but for the
filing of such registration statement; and (iii) would, in the good faith
judgment of the Company's Board of Directors, have a material adverse effect
upon the Company's ability to complete such significant transaction or upon the
terms on which such significant transaction could be completed.

     (d) The Company agrees to pay for all Registration Expenses (as defined in
the Registration Rights Agreement) with respect to the Shelf Registration
Statement; provided, however, that the Merrill Lynch Holders shall pay all
underwriting discounts, brokers fees and commissions and transfer taxes, if
any, relating to the sale or disposition of shares offered or sold under the
Shelf Registration Statement.

     (e) Except as provided herein to the contrary and except to the extent
that such terms not apply to resale registration statements filed under Rule
415 under the Securities Act, the terms and conditions governing the
registration procedures of the Shelf Registration Statement and the
indemnification rights provided with respect to the Shelf Registration
Statement shall be as set forth in Sections 5 and 6 of the Registration Rights
Agreement.

     Section 2. Miscellaneous.

     (a) Entire Agreement. The Registration Rights Agreement and the Stock
Purchase Agreement, as amended hereunder, constitute the entire agreement
between the Parties with respect to the subject matter hereof and supersedes
any prior understandings, agreements, or representations by or between the
Parties, written or oral, to the extent they relate in any way to the subject
matter hereof. Unless otherwise expressly provided for herein the Stock
Purchase Agreement shall remain in full force and effort.

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     (b) Counterparts This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original but all of which
together will constitute one and the same instrument.


                                   * * * * *

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     IN WITNESS WHEREOF, the Parties hereto have executed this Agreement as of
the date first above written.


BORG-WARNER SECURITY CORPORATION


By:________________________________________________
Name:  Timothy M. Wood
Title: Vice President and Chief Financial Officer


SELLERS:

MERCHANT BANKING L.P. NO. I
By: Merrill Lynch MBP Inc., General Partner


By:________________________________________________
Name:______________________________________________
Title:_____________________________________________


MERRILL LYNCH CAPITAL APPRECIATION
PARTNERSHIP NO. VIII, L.P.
By: Merrill Lynch LBO Partners, No. II, L.P., General Partner


By:________________________________________________
Name:______________________________________________
Title:_____________________________________________


ML OFFSHORE LBO PARTNERSHIP NO. VIII
By: Merrill Lynch LBO Partners, No. II, L.P., Investment General Partner
By: Merrill Lynch Capital Partners, Inc., General Partner


By:________________________________________________
Name:______________________________________________
Title:_____________________________________________


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ML EMPLOYEES LBO PARTNERSHIP NO. I, L.P.
By: ML Employees LBO Managers, Inc., General Partner


By:________________________________________________
Name:______________________________________________
Title:_____________________________________________


ML IBK POSITIONS, INC.


By:________________________________________________
Name:______________________________________________
Title:_____________________________________________