Robert Wesley Knighton, who was nicknamed "Bobby," was born on February 5, 1941, in Springfield, Missouri. His early life was troubled and complicated. His mother had eight husbands and many boyfriends, which created a chaotic home environment. Knighton did not often discuss his childhood, but it was marked by emotional and physical abuse.

At a young age, Knighton experienced significant hardships. When he was about six years old, he was humiliated at a Thanksgiving dinner where he was made to sit outside the family's home because he resembled his father. He faced violence from one of his mother's boyfriends, who hit him hard enough to require hospitalization.

Knighton's childhood was not just filled with emotional pain but also a lack of education. He attended school only until the fourth grade before he dropped out. When he was twelve years old, he was sent to a boy's reformatory. There, Knighton described a harsh environment where misbehavior was met with beatings and confinement in a cellar for days at a time.

Knighton's early criminal activity began in his teenage years. In 1968, he was convicted of armed robbery in Oklahoma and sentenced to ten years in prison. He had a hard life and did not have many positive influences or goals. At one point, he mentioned that he idolized Elvis Presley and dreamed of being a singer, but he struggled to find his way.

On September 15, 1973, Robert Wesley Knighton shot Claude Day and his son, Coffier Day, after an argument. Claude survived his injury, but Coffier was killed. After the shooting, Knighton kidnapped a young couple and their 6-year-old daughter, threatening the child’s life to coerce the parents. The kidnapping lasted 11 hours and ended when the woman attacked Knighton with a steak knife while he was buying food at a café. Knighton was arrested shortly after this incident.

Knighton was charged with manslaughter for Coffier's death, among other charges, and received a 30-year sentence in prison. He later joined a white supremacist gang while serving his sentence. In 1990, recently escaped from a halfway house, Knighton planned a crime spree with a woman and a teenage boy. They stole a van and began their journey to commit robberies and possible murders.

After visiting Knighton's mother for money, they murdered Frank Merrifield and his stepson, Ray Donahue, in Clinton, Missouri, taking their guns and cash. They traveled to Oklahoma, searching for homes to rob. Eventually, they targeted Richard and Virginia Denny. Knighton forced Richard into the house and, despite Richard’s pleas for life, shot both him and Virginia. The trio stole some items and continued their journey.

After drawing attention for suspicious behavior, they were arrested, and investigators discovered the murders. All three faced trial for the killings. Knighton’s accomplices testified against him in exchange for lighter sentences. Knighton admitted to the crimes during the trial and was convicted of first-degree murder. He was sentenced to death.

Robert Wesley Knighton was executed by lethal injection on May 27, 2003. In his final meal, he requested a large pepperoni pizza, a strawberry milkshake, onion rings, and banana cream pie. Before he died, he thanked his attorneys and made a brief statement, expressing a hope to reunite with a victim's daughter he had befriended while on death row.