In 1972, the establishment's founder, Umberto Ianniello, opened the restaurant at 129 Mulberry Street (at the northwest corner of Mulberry and Hester Streets). The restaurant was both the hangout of Umberto's son, reputed Mafia leader Matthew ("Matty the Horse") Ianniello and (according to Judge Edward Weinfeld of the Federal District Court in Manhattan) secretly owned by Matthew.
Two months after opening, on April 7, 1972, New York gangster Joe Gallo was shot and killed at the eatery, where his party of family and friends (including his daughter, wife, and bodyguard had stopped for an early morning snack after celebrating his 43rd birthday at the Copacabana. A rival gangster spotted him and sent in hitmen shortly after Gallo was seated at a butcher block table in a back corner. After sustaining five shots, Gallo stumbled out into the street and died.
Source: Wikipedia
I will bet revenues doubled at that place during the following weeks.
I just finished reading I Heard You Paint Houses, the Frank Sheeran story and confession of how he killed his friend, Jimmy Hoffa. His story on the Hoffa killing seems quite plausible. Apparently, the FBI had always tabbed Sheeran as the most likely suspect in Hoffa's disappearance.
In the book, Sheeran claimed to be the sole gunman who took out Joey Gallo on the orders of Russell Bufalino. I suppose that it is possible but that story doesn't seem to have quite the same credibility as his claims to have killed Hoffa.