Diane Downs shot dead her daughter and wounded her other children: ID investigates

20/20 on ID is investigating the disturbing case of Diane Downs, who appeared to shoot her three young children because her ex-lover said he didn’t want any kids in his life.

On May 19, 1983, Diane Downs was in a car with her three children in a rural area near Springfield, Oregon, when at some point, she stopped the car and opened fire on her kids. She also inflicted a gun wound on her left forearm, and then drove to the nearest hospital.

When they arrived at the hospital, 7-year-old Cheryl had already passed away, and 8-year-old Christie and 3-year-old Danny were severely injured.

When questioned by the authorities, Downs claimed that a man had attempted to carjack them. She said the stranger had waved them down and then opened fire at close range. However, the police and hospital staff were instantly suspicious of the mother due to her overly relaxed manner and inappropriate comments.

The police noted that the forensic evidence didn’t match her story; the gun splatter and gun powder were not consistent with how she described the attack.

Diane Downs was obsessed with Robert Knickerbocker

They then learned that Downs had been having an affair with a married man named Robert Knickerbocker. The pair had been having an affair in Arizona, where Downs lived until recently; however, Knickerbocker had wished to remain with his wife.

Unfortunately, Downs became obsessed with Knickerbocker and had stalked him before she moved to Oregon. He had told her that he didn’t want any children in his life. The police believe that Downs tried to kill her own children to persuade him to leave his wife and be with her.

Just nine months after the shooting, Downs was arrested and charged with murder and attempted murder of her own children.

At her trial, her surviving daughter, Christie, testified that her mother had shot her. In June 1984, Downs was found guilty and sentenced to 50 years in prison. She briefly escaped prison in July 1987 and was sentenced to a further five years on her recapture.

More from 20/20 on ID

Follow the links to read about more horrific murders profiled on 20/20 on ID.

In 1992, Raymond Rowe brutally raped and murdered schoolteacher Christy Mirack in her home in Lancaster, PA. Over the next 25 years, Rowe became a minor celebrity in the area as a DJ; however, he was finally put away when the police matched his DNA to the killers.

Amanda “Mandy” Stavik was kidnapped, raped, and murdered as she went jogging near her home in rural Washington state. The case grew cold for 30 years until her neighbor, Timothy Bass, was finally arrested for the crime.

My Mother’s Sins: Diane Downs airs in two parts in 20/20 on ID at  10/9c on Investigation Discovery.