The state parole board has approved Michael McDonald's release three times and Gov. Arnold Schwarzenegger has vetoed it each time, saying the convicted murderer showed a "lack of insight" into his crime because he still insisted he was innocent.

But a state appeals court says that neither the governor nor the board can insist on a confession before paroling a prisoner who, based on the evidence, is not dangerous.

State laws "prohibit requiring an admission of guilt as a condition for release on parole," the Second District Court of Appeal in Los Angeles said Tuesday. The court said McDonald's background, his behavior during 17 years in prison and psychological evaluations all indicate that he poses little risk of future violence.

The 3-0 ruling upheld a judge's order that freed McDonald on parole a year ago. Schwarzenegger, who wants to return him to prison, could appeal to the state Supreme Court.

McDonald was convicted of second-degree murder and sentenced to 15 years to life for the February 1992 slaying of 16-year-old Alexander Geraldo, who was stabbed in the neck and strangled with a guitar string in San Pedro (Los Angeles County).

Prosecutors said McDonald, then a 16-year-old member of the Reserve Officers Training Corps at a Long Beach high school, got his orders from an Army soldier who was jealous of Geraldo's involvement with his girlfriend and told members of a secret ROTC club to kill the youth.

Guitar strings like those found near Geraldo's body were discovered at McDonald's home, and another member of the ROTC club testified that McDonald had admitted the killing, the court said.

But McDonald said Geraldo was his best friend and that he had tried to arrange a truce between Geraldo and the club. He also said he had been home the night of the killing.

In prison, McDonald was a church clerk, helped with the Alternatives to Violence program, earned high school and community college degrees and took extensive vocational training, the appeals court said.

The Board of Parole Hearings found McDonald suitable for release in 2006, 2007 and 2008 and was overruled each time by Schwarzenegger, who appoints the board members. The governor's January 2009 veto said the heinous nature of the crime, and McDonald's lack of insight into his responsibility, showed he was still dangerous.

But the appeals court said McDonald's refusal to confess to the crime doesn't demonstrate either that he lacks insight or that he's prone to violence.

The court also said a 2008 state Supreme Court ruling requires the parole board and the governor to base their decisions on whether the inmate poses a threat to the public, and not merely on the circumstances of the crime.