Tommy Agro Killed DiSimone. The killing of DeSimone served several purposes. The Luchhese crew knew for many years that DeSimone and Jimmy Burke murdered Bentvigna. Tommy was doing alot of blow and was shooting his mouth and guns off too much. Right after Lufthansa I think Jimmy Burke wanted to Kill Tommmy so Paul Vario let the Gambinos know for sure who wacked their soldier. It was always suspected that it was Tommy and Burke but there was no real proof besides Burke was probably the biggest earner in Brooklyn/Queens so Vario would never allow him to get killed so Tommy was sacrificed.
John Gotti was not known outside the life at the time of Lufthansa and than when he got all Hollywood snitches came out of the woodwork saying he killed Tommy 2 guns. The last Tommy was seen was leaving the pizza parlor in Flatlands of a Luke soldier.
After Gotti became a big name Henry Hill said it was the Bergin crew that did Tommy but also by that time Henry always had a snootful of blow and bellyfull of vodka and his reliability was sagging as well as his money.
I would put my money on Tommy Agro, maybe Gene and Johnny Carnegs. De Simone was also on the shitlist for killing foxy Jerothe who was best friends with Foxy. There was no shortage of enemies.