Savages

Best friends Chon (Taylor Kitsch) and Ben (Aaron Taylor-Johnson) are marijuana growers in Laguna Beach, California. Chon, a former Navy SEAL, smuggled the seeds for the plants out of Afghanistan. Ben, a University of California, Berkeley graduate in business and botany, cultivates the marijuana. The seeds yield a particularly potent strain, which develops a wide customer base. Chon and Ben become wealthy, and Ben devotes time and money to charity work in Africa and Asia. They are both in a relationship with Ophelia Sage (Blake Lively).
The trio receives a video from Mexican drug-cartel enforcer Miguel "Lado" Arroyo (Benicio del Toro) of severed heads and a chainsaw, and Arroyo demands a meeting at which the cartel offers a partnership. Although Chon and Ben offer to hand over their network and get out of the business, the cartel wants their expertise and insists on a partnership. Chon and Ben make plans with Ophelia to go to Indonesia for a year, not telling her that they are fleeing the cartel. They speak to corrupt DEA agent Dennis Cain (John Travolta), who urges them to join the cartel. Ophelia is kidnapped by Lado's gang; Chon and Ben are notified of the kidnapping by a video call from cartel leader Elena SÃ¡nchez (Salma Hayek), who threatens to harm Ophelia if they decline the partnership.
They discuss the situation with Dennis, who tells them that Elena is facing the loss of her political connections in Mexico (foiling her efforts to move into the US). Since she has already lost most of her family, Dennis says that he has nothing on her that can help them. Chon stabs Dennis in the hand and demands DEA intelligence so they can attack Elena. With help from Chon's Navy SEAL friends, he and Ben attack a cartel money convoy and kill seven of Elena's men.
Ophelia, held in horrible conditions, demands to speak to whoever is in charge. Lado drugs and rapes her in retaliation for going over his head. Elena, traveling to the US to visit her daughter and deal with the escalating situation, has Ophelia brought with her. Chon and Ben frame high-ranking cartel member Alex (DemiÃ¡n Bichir) as an agent of Elena's rival, El Azul. With Dennis' help, they falsify evidence and give it to Lado. Lado tortures Alex and forces Ben to immolate him; Ophelia is forced to watch. He double-crosses Elena and begins working with El Azul.
Ben and Chon pay Dennis $3 million for information about Elena's daughter, Magda (Sandra Echeverria), and the name of his informant in Elena's cartel. They kidnap Magda and video-call Elena to establish that they are now in control. With Elena at their mercy, they arrange a desert meeting to exchange Ophelia and Magda at which snipers from both sides are in position. Elena asks who revealed her daughter's location, and Chon tells her it was Lado. She tries to kill Lado, but he shoots her first; a firefight erupts, and Chon is shot several times. Lado is shot in the back by Ben, but shoots him in the neck before Ophelia kills him. Ben is mortally wounded, and Chon injects him, Ophelia and himself with a fatal overdose so they can die together.
Ophelia wakes from a nightmare. At the meeting, Lado steals Elena's car and escapes as Dennis leads DEA agents to the scene. Everyone but Lado and Magda is arrested. Because Ben has incriminating information about Dennis, Dennis identifies Ben and Chon as his informants in the cartel and they are released. Elena is sentenced to thirty years in prison, and El Azul and Lado create a new cartel called the Azulados. Ben, Chon and Ophelia leave the country and live in a beachside hut, possibly in Indonesia. Ophelia wonders if they are living like savages.

Question: who shot lado in the back?
Answer: Ben