Ari Zadofian was an Armenian hitman, working for Diro Kesakhian.
Zadofian was one of Diro Kesakhian's closest enforcers and had previously worked for her ailing father. After Diro learned of the Strike Team's robbery of the Money Train, Zadofian was sent to murder Vic Mackey's family. However, the plan went sour when he was ambushed and shot in the stomach by Mackey's former partner/friend Shane, however Shane spared Zadofian who then fled from the Mackey residence to an unknown location.
Knowing that Zadofian was looking for them, Vic and Ronnie tracked him and found him hiding in a motel. They tied him to the bed, and squeezed him for information regarding the contract on Vic's family. Once Zadofian confirmed that he was responsible, Ronnie ordered him to place a cell phone call to Diro. Before Zadofian could answer, Ronnie shot him twice in the chest, killing him.
Shane, who was in the vicinity, entered the motel after Ronnie left and found Zadofian's corpse. In order to make it look like an Armenian Mafia slaying, Shane severed Zadofian's feet and left the scene.
It can be assumed that Vic exposed Ronnie as Zadofian's killer after agreeing to testify about all his crimes in order to gain immunity from Immigrations and Customs Enforcement (ICE).