Find out who was responsible for Richard Wright's overdose

Quite a long and a bit complicated quest. First you must have permission to speak with the head of the Wright family. (Be patient and offer to do this job without asking for a reward).

Talk with the Wright son outside the room for permission to investigate Richard's room. (An empty Jet canister should be located on the bookshelf in the room).

From this point on, talking with any of the suspects and then returning to the Wrights accomplishes the quest... But there's more for the complete picture.

Talk with Jagged Jimmy and have him examine the empty Jet canister and he will have you talk to Renesco.

In pressing Renesco, he will remember the Salvotores coming to him one day and rig the Jet to kill "someone".

Return to the Wright and tell him Renesco was used as a setup by the Salvatores to instigate a blood war between the Wrights and the Mordinos.