Like I have stated before, we didnt know Gotti was involved in the Borelli murder until Massino said so. Given that Gotti came of age during the time in the mob that guys actually had to commit murder to get straightened out, if I was a betting man I would bet on him having committed a murder. Given his ridiculous temper, and propensity for violence. Currently, there isnt and probably never will be any new informant from that era who would be able to shed light on this with direct knowledge of Gotti pulling the trigger.