Outfit and O.C. historians say there is no definitive answer relative to Accardo's involvement. He may or may not have been involved.

The one individual who was very likely involved was Fred " Killer" Burke. Guns taken from his home matched bullets from the massacre.

These guys liked to brag about participating in notorious events like the St. Val. Day's massacre and the assassination of President Kennedy, but most of the time no evidence can be found to prove the assertions. It doesn't mean they were not involved, just that it can't be proven.