Final Destination 5

Sam Lawton is on his way to a company retreat with his colleagues. While their bus crosses the North Bay Bridge, Sam has a premonition that the bridge will collapse, killing everyone on it, except for his ex-girlfriend Molly Harper, who he manages to get across the bridge safely. In a panic, he persuades several people to leave the bridge before it collapses, including Molly; his friends Nathan Sears and Peter Friedkin; Peter's girlfriend Candice Hooper; his boss Dennis Lapman; and co-workers Olivia Castle and Isaac Palmer. FBI agent Jim Block does not believe that Sam is responsible for the bridge collapse, but promises to keep his eye on him. At the memorial service, coroner William Bludworth mysteriously tells the survivors that "Death doesn't like to be cheated", and warns them to be careful. Believing this to be nonsense, they ignore his warnings and leave.
Later, Candice goes to gymnastics practice with Peter. A loose screw from a fan lands onto a balance beam, and when a gymnast lands on it she falls off in pain and knocks over the powdered chalk, which hits the fan and forms a cloud of chalk. This causes Candice to fly off the uneven bars, and she snaps her spine, leaving Peter devastated. The next day, Isaac is killed when his head is crushed by a falling Buddha statue during an acupuncture session at a Chinese spa. Bludworth, who has been present for both deaths, tells the remaining survivors that if they wish to cheat Death, they must kill someone who was never meant to die on the bridge, and thereby claim their remaining lifespan. On the same day, Olivia goes to an eye surgery clinic to treat her myopic vision. While the eye doctor is out looking for files the laser malfunctions, searing her eye and hand. She manages to free herself as Sam and Molly arrive to save her, but trips and falls out of the window onto a car below. Later, Sam realizes that the survivors are dying in the order they were meant to die on the bridge. He and Molly study Death's design and realize that Nathan is next on Death's list.
Meanwhile, Nathan, who has returned to the factory, accidentally kills his jerk co-worker, Roy Carson, during an argument by pushing him in front of a lifting hook, which impales him through the chin. Nathan relays this information to the remaining survivors, who realize he claimed Roy's remaining lifespan by killing him and therefore must be safe. When Dennis arrives to question Nathan about the incident a wrench launched by a belt sander hits him in the face, killing him.
That evening, Sam works at a restaurant, and after work asks his supervisor to reserve the restaurant for a date with Molly. Peter, who has become paranoid and insane after Candice's death, interrupts the date to tell them that he convinced himself he would be able to kill someone else in order to take their lifespan, and has decided to kill Molly. After Peter draws a gun, Sam and Molly both escape to the restaurant's kitchen. Agent Block overhears the shots from outside, but when he enters the restaurant he is shot and killed by Peter. Believing that he is now safe from Death, Peter decides to kill both Molly and Sam to remove any witnesses. Peter chases molly in which Sam intervenes. Peter and Sam fight and Peter knocks Sam out. Just as Peter is about to stab Molly with a kitchen knife, Sam awakens and stabs him in the back with a large skewer, killing him. Sam believes he has claimed Block's life.
Two weeks later, Sam and Molly board a Volee Airlines Flight 180 to Paris. As they take their seats a fight breaks out between two passengers (Alex Browning and Carter Horton), who are removed from the plane, along with several others. Upon takeoff, Sam overhears that one of the passengers had a vision of the plane's destruction, revealing that the movie is a prequel to the first film, but it is too late to leave and both he and Molly are killed when the plane explodes. At Roy's memorial, Nathan discovers from a co-worker that Roy's autopsy revealed he had a brain aneurysm that would have burst "any day now". As Nathan realizes he is still in danger, the landing gear from Flight 180 crashes through the roof and crushes him.

Question: Who kills Peter
Answer: Sam