Mason's parents were strict fundamentalist Pentecostals, [2] as a result of which they would subject their children to harsh physical, psychological and verbal abuse if any of them showed what they considered a "lack of enthusiasm" in religious activities.

Later on in life, both of his parents admitted that they beat David for even minuscule reasons, and Mason himself claimed that on at least two occasions, his mother had inflicted more than 100 hits during a punishment session with a belt, switch or pancake turner.

[2] In the mid-1960s, Mason began to exhibit concerning behavior and signs of mental illness - at the age of 8, his father found him standing in front of his younger brother's crib with a knife in his hand, for which he was beaten.

Unable to control his behavior, Mason's parents began to lock David in his room for prolonged periods of time, installing a grate with steel bars on the window.

[2][4] During this period, he attacked other children and teachers alike, earning a reputation as a bully, and attempted to set fire to neighboring houses, his school and the church.

He underwent a psychiatric reevaluation, which determined that he had an IQ of 110 and a good learning ability, but also showed signs of PTSD, for which he was sent to a boarding school with his parents' permission.

The following year, he dropped out of school shortly before finishing the 11th grade and enlisted in the Marine Corps, but quickly lost interest in military service.

During his first few weeks, Mason committed numerous offenses and was disciplined several times, resulting in his dismissal from the Marines four months later and his return to his parents' house.

Since he frequently visited her house, he knew that the elderly woman had a collection of rare antique coins, and due to her fear of robbers, Picard had shown him how the alarm system works, letting him know how to turn it off.

On March 6, 1980, in desperate need for cash, Mason went to Picard's house and, threatening her with a weapon, demanded that she hand over her coin collection, money and any other valuables.

During the investigation, the victim's neighbor, Paula White, told police that she had met the alleged killer, who was exiting the elevator at the ground floor, at around 4:00 pm.

On January 6, 1981, four weeks after the murder of Dorothy Lang, Mason drove past a patrol car in Alameda County near I-580, driving at high speeds in his Dodge Charger.

Trying to avoid pursuit, Mason exited the freeway and entered a residential area, where he passed several streets before he wound up at a dead-end, which forced him to leave the car.

On January 22, police officer Larry Schuchert visited Mason's parents' home in San Lorenzo and spoke to his mother and his brother Mark.

During his interrogation at the police station, he again reiterated his claims from the tape, and additionally confessed to the murder of his 55-year-old lover Robert Groff, a dog business owner who lived in a trailer in Butte County.

After the body was discovered, all the inmates were questioned as to what had happened, and during the investigation, Shorter confessed that he and Mason had killed him, a claim later confirmed by Yancey and Grant.

However, the court dismissed this as proof of his innocence, since Mason's brother and his close friend, Karen Warden, also worked there, and could have easily falsified the records.

[1] In the early 1990s, his lawyer drew up an appeal, arguing that his client's sentence be commuted to life imprisonment, citing his abusive childhood and mental issues.

Despite the likelihood of a new trial and the overturning of his death sentence, Mason voluntarily withdrew his appeal in June 1993, setting his execution date for August 24, 1993.

[1] After refusing to file appeals, in August 1993, Mason's lawyer, Charles Marson, claimed that his client was insane and unable to make decisions of this magnitude of his own accord.

[4] In case he changed his mind, prison administration installed a telephone in the gas chamber by which Mason, if he so desired, could contact his new lawyer Mike Brady.