As told to me many years ago by an insider.
Piro accepted the bribe.
After the undercover Fed left, Piro was joined by a friend who had seen Piro and the Fed together. Piro's friend had gone to high school with the undercover Fed and tipped off Piro as to what his real name was and that he worked for the Federal Govt.
Piro gave the money back just in time.
and there were guilt-by-association whispers about his link, early in his career, with Vincent J. Piro, the Somerville lawmaker who took $5,000 in cash from an undercover FBI agent but returned the money before he was indicted and beat an extortion rap in 1985.