Faster

The film begins with Driver (Dwayne Johnson) being released from prison after talking to the warden (Tom Berenger) who tells him he should be a better person. He exits curtly, breaks into a run, seemingly set on something. He runs until he retrieves his Chevelle LS5 SS recreation (1970 Chevelle front and 1971 Chevelle rear end) drives to an office in Bakersfield where he kills a man (Courtney Gains).Driver then goes to the man (Mike Epps) who gave him the car and the gun and forces him to give him the names and info for the rest of some list he compiled for Driver. Meanwhile, Driver is being tracked down by detective Cicero (Carla Gugino) and Cop (Billy Bob Thornton), a retiring cop whose life is off track and suffering from a drug habit. They investigate the office crime scene and video from the scene. Cicero gets a break in the case when she recognizes Driver. Later, a nameless hitman 'Killer' (Oliver Jackson-Cohen) is hired to kill Driver. Killer tells his girlfriend Lily (Maggie Grace) that it is his last job, and while he seems to feel the conflict between his professional life and love life with Lily, he decides to go.Driver heads to the second name on his list. It is an old man who films his own personal snuff films, and he is in the middle of filming himself taking advantage of a girl he drugged when Driver busts in the door and shoots him dead. Killer has tracked down Driver and initiates a gun fight in the hallway, but Driver escapes. This affects Killer philosophically, who proposes to his girlfriend and takes the case personally.It is revealed that Cop has a drug problem, along with his girlfriend Marina (Moon Bloodgood). Cop and Detective are investigating Driver's past and discover he was double crossed. Cicero remembered Driver from a video of his brother's death, filmed by the man Driver has just killed. On tape, Driver is shot in the head by an unidentified man, but narrowly survives, needing surgery and a metal plate to fix his skull.Driver goes to his old girlfriend's (Jennifer Carpenter) house. She knows he's killing the people in the video and tells him she hopes he succeeds. Driver then goes to Nevada to kill the man who slit his brother's throat. He works as a bouncer in a strip club, and due to security, Driver could not bring his gun inside, so instead he stabs him several times with an ice pick and leaves him to die in the bathroom. Meanwhile, both Cop and Killer have gotten word that the man survived the stabbing and is in the hospital. Knowing Driver will go back to finish him off, they converge on the place.Driver enters the hospital and kills the man while he is in surgery. Cop attempts to bring down Driver but is unsuccessful, however Driver spares his life after seeing his badge. While driving away from the hospital, Driver encounters Killer. After a high speed chase on the highway, Killer manages to shoot Driver in the neck after Driver shoots out his tires.Driver goes to the second-to-last name on the list, who turns out to be his father. He believed that his father was the one who arranged to have him and his brother killed, after they refused to give him a share of the money they stole in a bank job they pulled together. He finds out that his father died years before, and his mother stitches the gunshot wound on his neck before he sets off to finish the list. It is later revealed that his mother had an affair with another man who was apparently of a different ethnic background and that the old man abused Driver because of it. The last man is a traveling evangelist, and after his service is over and everyone has left, Driver confronts him. The evangelist knows why he is there, and tries to tell him that he has turned his life around, begging for forgiveness. Driver spares him and goes to leave when he is confronted by Killer.Detective Cicero learns the true identity of the man who shot Driver. She hurries to the church with Cop already on the scene. Killer tells Driver to pick up his gun so they can have a true test of skill. But Driver declines, saying he has no fight with him. Killer then explains he wanted to be better since he could not walk when he was a child.Cop walks in and shoots Driver in the head. It is revealed that Cop was the man who shot Driver in the video. He gives Killer the money for the job, but he declines, because he wasn't the one who killed him. Killer then departs, telling Cop never to contact him again, likely signifying the end of his career as an assassin. Killer calls his wife, telling her that he is coming home. Cop calls his girlfriend, telling her that they will be okay because he closed the case and how he has been reading up on women. It is revealed in pieces that the girl we thought was Drivers but was actually Gary's and a C.I for the Cop, and let the info slip about the bank job and the cop then put together the crew to take out Gary and Driver. Suddenly, he is shot by Driver, who survived the shot due to the metal plate in his skull.Detective Cicero arrives on the scene after Driver has already left and finds Cop's body who promptly decides to cover up Cop's involvement in the whole mess presumably to allow his family to receive his benefits and retain some sort of dignity. The movie ends with Driver scattering his brother's ashes in the sea and driving off into the sunset as the avenging spirit of his brother Gary.

Question: who covered up Cop's involvement?
Answer: Detective Cicero