Diane Downs was born on August 7, 1955, in Phoenix, Arizona. Her parents were Wesley and Willadene Frederickson. Diane had a difficult relationship with her father, who she later accused of abuse, though she later retracted these allegations.

Diane grew up in a strict household where she wasn't allowed to wear trendy clothes or makeup, leading to bullying at school. She became more rebellious at 14 and eventually graduated from Moon Valley High School, where she met her future husband, Steve Downs. Despite her parents' objections, she married Steve in 1973 after running away from home.

Diane attended Pacific Coast Baptist Bible College but was expelled for promiscuous behavior after one year. She returned to Arizona and later had three children: Christie Ann, Cheryl Lynn, and Stephen Daniel. Her marriage to Steve ended in 1980 due to infidelity and financial issues. Before her arrest, she worked as a postal worker in Oregon.

On May 19, 1983, Diane Downs shot her three children and drove them to the hospital. Her daughter Cheryl died, while Christie and Danny were severely injured. Downs claimed a strange man attacked them, but police doubted her story due to her calm demeanor and inconsistent evidence. Investigators discovered Downs had a motive: she wanted to be free from her children to pursue a relationship with a man who didn't want kids. Downs was convicted of murder and attempted murder, largely based on Christie’s testimony, and was sentenced to life in prison.

Diane Downs was sentenced to life in prison, eligible for parole after 25 years. Despite applying for parole multiple times, she has consistently been denied. Downs continues to claim innocence, sticking to her original story that a stranger shot her and her children. Psychiatrists diagnosed her with narcissistic, histrionic, and antisocial personality disorders. She escaped prison once in 1987 but was quickly recaptured and given an additional five-year sentence.

Downs' two surviving children, Christie and Danny, were adopted by the prosecutor, Fred Hugi, and his wife. Christie, who testified against her mother, has a speech disability. Downs gave birth to another daughter, Rebecca, after the trial. Rebecca was adopted and has since spoken publicly about her biological mother, expressing regret for having contacted her. Ann Rule's book "Small Sacrifices" and a TV movie by the same name detail the case and its impact on Downs' children.