In May 2014, a Boston transit cop pulled an inebriated man back onto a subway platform moments before he would have fallen on the tracks. So how did the man end up in a hospital with a face full of bruises? At the time, MBTA’s chief called his cop a hero, described his actions as “appropriate,” and MBTA released an edited surveillance tape that cuts off before you would see the detective repeatedly punching the man in the face on the platform floor after saving him. The victim, Anthony Ferrier, has hired a lawyer and is suing MBTA and Detective Sean Conway for excessive force. After months of stonewalling by authorities, a Boston TV station has obtained the complete tape, and is raising questions about police deception and coverup of a violent and unnecessary beating of a civilian by a cop.