A California death row inmate is claiming his innocence, arguing he was framed for the stabbing deaths of four people, two of whom were children, at a suburban Los Angeles home in 1983, prompting State Governor Gavin Newsom to order an independent investigation.

The inmate, the 63-year-old Kevin Cooper, has been seeking gubernatorial clemency since 2016. Newsom said he was not taking any sides despite ordering the independent investigation of Cooper’s case.

Death Row Inmate’s Innocence

A law firm was appointed to review Cooper’s court records and all facts and evidence related to his case. These include the ones that have not been made public or shown in trials and appellate records. The firm was also given the task of reviewing DNA results that Newsom previously ordered.

While the order said the tests had been completed, Cooper’s lawyers and the San Bernardino County district attorney’s office had completely opposite beliefs on how they affected the suspect’s claims. Cooper’s attorney, Norman Hile, said the order was a good start to his client’s benefit.

“We are confident that a thorough review will demonstrate that Kevin Cooper is innocent and should be released from prison,” Hile said.

Authorities convicted Cooper in 1983 for the fatal attack in Chino Hills, found east of Los Angeles. The victims of the crime included Doug and Peggy Ryen, their 10-year-old daughter, Jessica, and their 8-year-old son, Joshua. The four were sleeping with an 11-year-old boy, Christopher Hughes, a neighbor when the incident occurred.

Investigators said the victims were stabbed more than 140 times collectively with an ice pick, knife, and hatchet. They said Joshua survived the encounter despite having his throat slashed.

Previous DNA test results showed that Cooper was inside Ryen’s home smoking cigarettes in a stolen station wagon, San Bernardino County prosecutors said. Cooper escaped from prison two days before the fatal incident. Prosecutors also claimed the blood of the suspect and one of the victims was found on a T-shirt left on a road leading away from the residence where the crime was committed.

However, Cooper argued that he was framed by investigators who planted his blood on the T-shirt. He accused officials of manufacturing, mishandling, planting, tampering with, or otherwise tainting trial evidence to falsely convict him of the crime.

Many who supported Cooper’s claims said there were other evidence materials that were not tested, including hair samples that could have belonged to multiple killers who were white or Latino, NBC News reported.