Locascio was convicted for his involvement in the murder of Louie DiBono. Many people believe that this was a bad rap.
Supposedly Frankie was in the Cerelli apartment when Gotti talked about why he ordered it,stating that DiBono was killed because he refused to come in when Gotti called him
This would seem to indicate that this was the first that FL heard about it.
Allegedly,prior to the hit,he suggested that Gotti "fine" DiBono for not coming when Gotti summoned him instead of killing him.
Gravano also said the Frankie was not involved,but conveniently left this out when being de-briefed after flipping.
The Bull said he didn't bring it up,because they never asked him.
There are pros and cons to all of this speculation,so I don't know that a definitive finding will ever be known.