Marcus Delon Wesson was born on August 22, 1946, in Kansas. He was the oldest of four children in his family. His parents were Benjamin and Carrie Wesson. Carrie, his mother, raised Marcus in the Seventh-day Adventist Church. Marcus described her as a religious fanatic. His father, Benjamin, was an alcoholic and was abusive. He left the family when Marcus was still a child.

In the early 1960s, the Wesson family moved to San Bernardino, California. Marcus struggled academically and eventually dropped out of high school. After leaving school, he joined the U.S. Army. He served from 1966 to 1968 and worked as an ambulance driver. During his service, he was deployed to Vietnam.

After his military service, Wesson moved in with an older woman named Rosemary Solorio. Rosemary had eight children. In 1971, she gave birth to Wesson's son. Wesson later began a controversial and troubling relationship with her daughter, Elizabeth. He married her when she was just 14 years old. Over the years, Wesson fathered a total of ten children with Elizabeth.

Wesson did not hold a steady job and mostly lived off welfare. He often moved his family into run-down houses, boats, or vacant spaces. He was known to have a troubled and abusive relationship with his wife and children. Wesson's home life was very strict, and he taught his children from his own version of the Bible. He told them that he was a god-like figure and expected them to obey him without question.

On March 12, 2004, a standoff occurred at Marcus Wesson's home in Fresno, California. Several members of his extended family, along with two of his nieces who had rebelled against him, came to demand the release of their children. The Fresno police were called to the scene, where Wesson asked them to wait at the door before going back inside his house. When he returned, his clothes were stained with blood.

During the standoff, witnesses reported hearing gunshots, but police officers did not hear them. After the situation was resolved, police discovered nine bodies inside Wesson's home. The victims included two of Wesson's daughters and seven of their children. They were found in a bedroom that contained antique coffins. Each victim had been shot through the eye.

The children who were not present during the incident survived. Following the murders, Wesson was arrested, and a trial was held. Wesson's defense claimed that his 25-year-old daughter, Sebhrenah, had committed the murders and then killed herself. A .22 caliber handgun was found with her body, and her DNA was on the gun. There was no gunpowder residue found on Wesson's hands at the time of his arrest.

Despite the defense's arguments, Wesson was convicted of nine counts of first-degree murder on June 17, 2005, as well as 14 counts of rape and the molestation of his daughters and nieces. He was sentenced to death on June 27, 2005. The house where the murders took place was later demolished. Wesson is currently incarcerated in San Quentin State Prison.