his name, john o'malley, an investigator for the u.s. attorney in new york.ing eric's letter, o'malley made a personal trip to see eric in sing sing. >> immediately john o'malley just stood up and he asked me, "did you write this letter?" and i said, "yes." he shook my hand. and he said, "i'm sorry." and i said, "sorry for what?" he says, you know, "i know you're innocent." when he said that, i said, "what are you talking about, sir?" he said, "listen, i know the guys who committed this crime." >> reporter: how did o'malley know? it turns out o'malley worked with detective forcelli on that gang case ten years earlier. and back then, those two gang members, jose and gilbert, actually confessed the cab driver shooting to o'malley. >> he said, "when i read this letter, everything just came back to me from that day. i put it all together from that day when these guys confessed to me." >> reporter: o'malley didn't want to appear on camera but told us he also checked with the nypd after getting those confessions in 2002, and like forecelli before him, o'malley was