John Joseph O'Brien ( September 11 , 1919 – October 16 , 2001 ) was an American civil servant who investigated the assassination of President John F. Kennedy . Born in Somerville , Massachusetts , O'Brien received his B.B.A. degree in law and business , cum laude , from Northeastern University , Boston . He received his M.A. degree in the field of governmental administration from George Washington University , Washington , D.C. , and in 1941 joined the Bureau of Internal Revenue . After service in the U.S. Coast Guard , O'Brien resumed his work as an Internal Revenue Service investigator . O'Brien was appointed as a staff member for the Warren Commission in 1963 . Their purpose was to investigate the assassination of President Kennedy . After completion of the Warren Commission , he took the post of Assistant Chief of the Inspection Services Investigations Branch , in the National Office of Internal Revenue
the assassination
Assassination of John F. Kennedy
John J. O'Brien (civil servant)