Actually another version, acording the Joe Iannuzzi's biography Joe Dogs was that Tom Agro, a made Gambino memeber killed Tommy, on Gotti's recomendation. Joe Dogs said T.A. as Agro was known also killed another Desimmone, who had ratted soem goodfellas out. Their brother Bobby was a member or Agro's and Iannuzzi's crew in Fla.

Agro, and Desimone were both convited and jailed when Agro turned and wore a wire for the FBI.

I recommend Joe Dog's as a good read.