James B. Clark Jr. was born on February 8, 1957, in Seaford, Delaware. He was adopted by Elizabeth and James B. Clark Sr. when he was a young child. The names of his birth parents remain unknown.

At the age of two, James began to show aggressive behavior. He frequently attacked other children, which led to him being expelled from two pre-kindergarten programs. By the time he turned five, he started receiving psychotherapy and medication to help with his behavior.

In 1965, when he was eight years old, James attacked another child. He cut the child's face badly enough that it required hospitalization. Because of this incident, he was sent to a psychiatric treatment program in Maryland, where he stayed for three years.

In December 1969, after being expelled from school again, James was sent to the Governor Bacon Health Center for residential treatment. He lived there for about a year and a half. The center reported that he had "moderately improved" during his time there. He was diagnosed with passive-aggressive personality disorder and schizoid personality disorder.

James B. Clark Jr. committed serious crimes throughout his life. On May 22, 1994, he killed his adoptive parents. He was motivated by a desire to collect their life insurance money. This crime occurred just one month after he was released on parole for a previous conviction.

Before this, in 1973, Clark had abducted a three-year-old girl from her backyard. He took her into the woods, where he beat and choked her. He was charged with kidnapping and assault with intent to commit murder. His original conviction was later reversed. He eventually pleaded no contest to some of the charges and received a 30-year prison sentence.

While in prison, Clark had further issues. In 1977, he pleaded guilty to third degree assault for attacking a prison officer.

In September 1994, after he confessed to killing his parents, Clark pleaded guilty to two counts of first-degree murder. He was sentenced to death. He waived his appeals, which led to his execution by lethal injection on April 19, 1996.