EXHIBIT 23.3 

                                 ALEX. BROWN 
                   AMERICA'S OLDEST INVESTMENT BANKING FIRM 
                               ESTABLISHED 1800 

   
                                                              January 21, 1997 
Video Sentry Corporation 
6365 Carlson Drive 
Eden Prairie, Minnesota 55346 


Dear Sirs: 

         Alex.  Brown  hereby  gives you  approval  to  publish  or refer to our
fairness   opinion   concerning   the  KNOGO   transaction   in  Video  Sentry's
proxy/prospectus. Alex. Brown will not be deemed an expert as defined by Section
7a of the Securities Act of 1933 with regard to this matter.


                                        Very truly yours, 

                                        ALEX. BROWN & SONS INCORPORATED 


                                        By: /s/ Paul D. Mellin 
                                            ------------------------------------





                         ALEX. BROWN & SONS INCORPORATED
                  ONE SOUTH STREET o BALTIMORE, MARYLAND 21202
                   o TELEPHONE: (410) 727-1700 o TELEX: 198186