Wouldn't it have been insanely easy for the FBI to identify John?

When John gets arrested with those three goons, the Donnelly has them all interrogated and digs through their lives to try and figure out which one is the Man in the Suit. Did he and every other cop and agent involved forget by that point, there was tons of people who saw John and could identify him? All Donnelly had to do was go to a some of the witnesses and criminals John had interacted with, and showed them a picture of the four men and see who they recognized. Boom. Done. Even if some witnesses refused to help because they didnt want to hurt John, I'm sure all the people he beat up and kneecapped would help.