The California Supreme Court upheld the death sentence Thursday given to convicted serial killer Charles Ng who’s been on death row for 23 years, according to court records.

Ng, who is now 61, was convicted in 1999 on 11 counts of murder for the murders of six men, three women, and two baby boys from 1984 to 1985.

His accomplice Leonard Lake killed himself in 1985 with a cyanide capsule after he was arrested on possession of a firearm with a silencer, according to court records.

Police had not started questioning Lake about the murders at the time of his death.

The two men went on a kidnapping spree in Northern California, hiding their victims in a secret bunker on a remote 2 1/2-acre Sierra Nevada fenced-in compound just 150 miles east of San Francisco, according to FoxNews5.

Lake, who was an avid doomsday prepper, had built the bunker in fear of a nuclear war but used it with Ng as a house of horrors, with two rooms set up like prison cells behind a hidden doorway.

Ng fled to Canada after Lake killed himself but was arrested in Calgary, Alberta, for shoplifting and attacking a security guard. Already a fugitive in the United States, the Canadian Supreme Court sent him back to the States after six years of fighting extradition.

Ng’s lawyer at the time said that since Canada did not have the death penalty and the United States, specifically California, does, it would be cruel to send him back to face possible death.

The Canadian Supreme Court said, “cruel and unusual punishment does not apply because any executions would be carried out under U.S. law against U.S. citizens for crimes committed in the United States.”

After being extradited to the United States in 1991, his trial in California didn’t begin until 1998 due to Ng and his defense delaying the court proceedings with various motions.

The two men had documented their kills in a 250-page diary and videotapes, according to the Associated Press.

Ng claimed to have no role in the killings and told the court Lake acted alone. When proved in court to be involved, his defense later argued that he was under the influence of Lake, who orchestrated the killings.

Police said Ng appears on some of the videotapes found at the crime scene, most notably one in which he threatens a terrified woman with a knife.

The way Ng and Lake tortured and dismembered their victims still has police attempting to identify the remains thirty-seven years later. With high estimates believing the murderous duo killed close to 25 victims.

To date, it was one of the longest, most expensive trials in California history for the amounts of delays brought by the defense, according to FoxNews5.

Gov. Gavin Newsom has a moratorium on the death penalty in California as long as he is governor. Ng still has the possibility of other federal appeals.