The Getaway

Carter "Doc" McCoy (McQueen), in prison in Texas, is denied parole. When his wife Carol (MacGraw) visits him, he tells her to do whatever necessary to make a deal with Jack Benyon (Johnson), a corrupt businessman in San Antonio.
Benyon uses his influence and gets Doc paroled on the condition that he takes part in a bank robbery with two of his minions, Rudy (Lettieri) and Frank (Bo Hopkins). During the robbery, Frank kills a guard. Rudy attempts a doublecross, shooting Frank and drawing a gun on Doc, who beats him to the draw and shoots Rudy several times.
Doc meets with Benyon, who attempts a doublecross before Carol shoots and kills him. Doc realizes that Carol had sex with Benyon to secure his release from prison. Doc angrily gathers up the money and, after a bitter quarrel, the couple flees for the border at El Paso.
A bloodied Rudy, having secretly worn a bulletproof vest, is alive. He forces rural veterinarian Harold (Jack Dodson) and his young wife Fran (Sally Struthers) to treat his injuries, then kidnaps them to pursue Doc and Carol.
Benyon's brother Cully (Roy Jenson) and his thugs also pursue the McCoys. At a train station, a shifty con man (Richard Bright) swaps locker keys with Carol and steals their bag of money. Doc follows him onto a train and forcefully takes it back. The injured con man and witnesses are taken to the police station, where they identify Doc's mug shot.
Carol buys a car while Doc steals a shotgun, leading to several shoot-outs and police chases. The couple escapes by hiding in a large trash bin, only to end up in the back of a garbage truck and dumped at the local landfill. Filthy and frustrated, they argue about whether to stay together or split up. They decide to see things through.
Rudy's attraction to the veterinarian's wife results in the two having sex in front of her husband. Humiliated, the vet hangs himself in a motel bathroom. Rudy and Fran move on, barely acknowledging the suicide. They arrive at an El Paso hotel used by criminals as a safe house, aware that the McCoys will be heading to the same place.
Doc and Carol check into a room on the same floor. They ask for food to be delivered; but the manager, Laughlin (Dub Taylor), says he is working alone and can't leave the desk. Doc soon realizes that Laughlin sent away his family because something is about to happen. He urges Carol to dress quickly so they can escape.
An armed Rudy comes to their door while Fran poses as a delivery girl who needs to be paid for the food. Peering from an adjacent doorway, Doc is surprised to see Rudy alive. He sneaks up behind Rudy and knocks him out, and does the same to the screaming Fran.
Cully and his thugs arrive as the McCoys try to leave. A violent gunfight ensues in the halls, stairwell, and elevator; and all of Cully's men are killed but one, whom Doc allows to walk away. Cully himself dies when the elevator he is in crashes to the bottom of the shaft. Rudy comes to his senses and follows them outside, but Doc shoots and kills him on a fire escape.
With the police en route, the couple hijack a pickup truck and force the driver, a cooperative old cowboy (Slim Pickens), to take them to Mexico. After crossing the border, Doc and Carol pay the cowboy $30,000 for his truck. Overjoyed, the cowboy heads back to El Paso on foot, while the couple continues on into Mexico.

Question: Who kills a guard?
Answer: Frank.