his name is reggie graham. >> reggie graham served in the narcotics field unit. ator tracked on a former undercover officer who had worked with graham for years. >> we worked in the squad together. i talked to him every day. >> jeffrey walker was not involved in meek mill's case but remembers graham talking about his arrest. >> i remember sitting at my desk and reggie graham's -- he was doing paperwork and we all talking. reggie graham was talking about it kid named meek mill. i distinctly remember him saying he arrested this kid, he beat this kid, and ripped a rope braids out of his head. >> walker said graham was a dirty cop and he should know because he was one too. >> i participated with reggie on one particular job in 2003 where i watched him fabricate evidence. >> in 2013, walker was arrested by the fbi for stealing money from a drug deal for exchange for a letter prison sentence, he pleaded guilty to attempted robbery and testified against fellow officers. so far, his information has led to more than 1000 overturned convictions in philadelphia. brindle was