Jon Scott Dunkle was born on October 11, 1960, in Los Angeles, California. He grew up in a typical suburban environment. Not much is known about his family or early childhood. However, he was raised in an area near the bustling city of Los Angeles.

On November 8, 1981, 15-year-old John Thomas Davies disappeared from his home in Belmont. This case raised concerns and drew attention to the issue of missing and abused children. The Davies family became advocates for change, helping to create the Violent Crimes Information Center.

On November 5, 1982, Steve Murphy was involved in a hit-and-run while walking home. He was placed in the trunk of the car and taken to a remote area, where he was dumped in a ravine. Days later, on December 31, Dunkle assaulted another boy, Monte Hansen, again using a two-by-four board. Both Murphy and Hansen survived these attacks.

The next significant incident occurred on October 2, 1984. Twelve-year-old Lance Turner was found dead near Water Dog Lake in Belmont. He had been stabbed 23 times. Weeks after his murder, Turner's grandmother received a strange phone call from a person claiming to be responsible for the crime.

On July 2, 1985, twelve-year-old Sean Gregory Dannehl went missing while riding his bike. His body was discovered six days later near the American River. The details revealed during Dunkle's trial were disturbing. Dannehl was forced to remove his clothing before being stabbed in vital areas, and after his death, Dunkle inflicted further harm.

Dunkle was arrested on April 4, 1985, for burglary. He was observed entering a house while police were monitoring the area. Later, in November 1985, he faced charges related to the hit-and-run incident involving Murphy when evidence linked him to that event.

For the burglary, Dunkle received a sentence of six years in prison. He was later convicted of the murders of John Davies and Lance Turner on December 7, 1989, and sentenced to death in January 1990. In 1994, he was given a life sentence without the chance of parole for the murder of Sean Dannehl.

Dunkle was diagnosed with schizophrenia during his time in prison. Reports indicate troubling behavior, including self-harm and delusions. In 2002, he was assigned a legal guardian due to his mental health condition. The Supreme Court confirmed his death sentence in 2005.