Also find another theory on it

http://goodfellas.martin-scorsese.net/information/real_story_tommydesimone.html

Tommy's real name was Tommy DeSimone, and was played by Joe Pesci in the film. The real life Tommy was much taller, although his menace was much the same.

Tommy was suspected of being on the Lufthansa job because an employee noticed one of the robbers had very shiny shoes (Tommy was well known for his dapper dressing and immaculate shoes).

He was murdered for a couple of reasons. First, he killed Batts, a made man of the Gambino crew. Second, he fooled around with another Gambino's wife. A made man as well, Foxy was in prison during this time, however, his capo did not want to exact revenge at that time. According to Joseph "Joe Dogs" Iannuzzi, Tommy Agro did the hit on DeSimone. Another possibility, although less supported, is that Paolo LiCastri was the hit man. In any case, a sit-down was conducted between Paul Vario and the Luccheses, and the Gambinos to order the hit.