Mark Edward Gardner was born on May 4, 1956, in the United States. Prior to his arrest for triple homicide in 1985, Gardner had a long criminal history that included convictions for armed robbery and violations of parole. At the time of the murders, he was 29 years old and living a transient lifestyle, drifting between states and evading law enforcement. He was also wanted on an active arrest warrant out of Illinois for another robbery at the time of the Arkansas murders.

Gardner’s background included prior incarceration, and he had reportedly exhibited violent behavior even while behind bars. After his arrest, Gardner made bizarre claims, stating that "demons made him do it", a statement that was brought up during his trial as part of his defense. Despite these claims, he was declared competent to stand trial and fully responsible for his actions.

While incarcerated on death row, Gardner was accused of sexually assaulting another inmate, Damien Echols, one of the men convicted in the infamous West Memphis Three case. Echols later described being raped and beaten by Gardner while imprisoned. The allegations never resulted in charges, but were widely discussed in subsequent appeals related to the West Memphis Three.

On December 12, 1985, Mark Edward Gardner brutally murdered three members of the Joyce family in Sebastian County, Arkansas. Joe Joyce had just returned home from a funeral, and his daughter Sara Joyce McCurdy, who was visiting for lunch while her husband was on Air National Guard duty, was at the house with her mother, Martha Joyce.

Gardner entered the family home, tied all three victims up, and suffocated them by placing tape over their noses and mouths. He used a wire coat hanger to strangle Martha, adding to the horror. Gardner then raped and murdered Sara. After the killings, he ransacked the home, stole jewelry, and fled in the family car.

When Gardner was arrested, authorities found some of the Joyce family's stolen jewelry in his possession. During questioning, he claimed to have also killed a man in New York, though that was never confirmed. At trial, Gardner's defense attempted to argue that he was insane, citing his statements about demonic possession, but the jury did not accept it. He was found guilty on all counts and sentenced to death in 1986.

After spending over a decade on death row, Mark Edward Gardner was executed by lethal injection on September 8, 1999, at the age of 43.