Nicholas Vargas

A San Bruno man accused of helping kill an acquaintance in his parent's home as they slept before dragging the body down the driveway pleaded no contest to second-degree murder using a deadly weapon but a jury will decide if he should be hospitalized as insane rather than serve 16 years to life in prison.

Nicholas Jose Vargas, 26, changed his plea from guilty Friday but maintains his secondary plea of not guilty by reason of insanity. A jury in May will conclude if Vargas knew what he was doing on April 10, 2011 when he and co-defendant Brandon David Thompson allegedly killed Christopher Chastain, 23, inside the home of Vargas' parents on Cypress Avenue.

"We believe this settlement is reasonable and we do believe he was sane at the time. Hopefully, a jury agrees," said District Attorney Steve Wagstaffe.

Wagstaffe did not know if Vargas may be called as a prosecution witness in Thompson's trial but said that was not a requirement of the plea deal.

Thompson, 28, is scheduled for a jury trial May 13, the same day as Vargas' sanity trial. Last year, court-appointed doctors split on whether they believed Vargas was insane. Doctors also concluded Vargas was mentally competent to help defend himself against charges stemming from the attack.

A motive in Chastain's death remains unclear although investigators initially said Vargas may have thought Chastain had harmed his sister in some way.

"It remains totally murky and the story about the sister appears to have no foundation. Maybe we will learn more in trial," Wagstaffe said.

According to prosecutors, Vargas placed a plastic bag over Chastain's head and hit him twice with a pipe wrench while Thompson stabbed him twice in the abdomen with a kitchen knife.

The defendants reportedly dragged Chastain's body down the driveway to Vargas' Honda Accord but could not lift the man who weighed 275 pounds. Prosecutors say Thompson left the scene and Vargas contacted his father inside who followed the blood to Chastain's body and called 911.

Vargas has no prior criminal history in San Mateo County, according to court records. Thompson, though, was on parole for a 2009 stolen vehicle conviction which came with a two-year prison sentence.

If Vargas is found sane, he must serve 16 years before being eligible for parole.

Both men remain in custody without bail.

Defense attorney Connie O'Brien could not be reached for comment.

michelle@smdailyjournal.com

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