SANDPOINT - A convicted sex offender charged in connection with the disappearance and death of a 6-year-old California boy waived his right to extradition on Monday.

Kenneth Kasten Rasmuson's waiver means he will not challenge his return to California to face a charge of murder.

Rasmuson, 53, is still listed as an inmate at the Bonner County Jail. Sheriff Daryl Wheeler said Rasmuson's return to California is imminent.

Rasmuson is implicated in the death of Jeffrey Vargo, who was found dead at a construction site in Pamona in 1981. Vargo's partially clothed body was discovered a day after he went missing while riding his bike to a fireworks stand in Anaheim.

Pamona police confirmed in 1997 that they reopened the investigation into Vargo's killing, but the case went cold again, according to the Los Angeles Times. Investigators would periodically take up the case and review evidence.

Investigators told the boy's father, Bob, that DNA testing had identified Rasmuson as the boy's killer a couple of months ago.

Authorities in Idaho and California began collaborating on surveillance of Rasmuson and the collection of a DNA sample. Sandpoint police declined to divulge how the sample was collected.

"We have been working for the last couple of months in getting an arrest warrant," Sandpoint police Sgt. Steven Chamberlain said on Saturday.

Rasmuson has resided at 612 South Third Ave. since 2010. Sandpoint police received a slew of calls and email messages about Rasmuson's presence in the neighborhood.

People in the neighborhood objected to Rasmuson's presence and his home's proximity to a small city park on the Pend Oreille River where children were known to congregate.

Rasmuson was listed as a violent sex predator when he relocated to Idaho, having been convicted of forcible lewd conduct in Santa Barbara and Los Angeles counties in 1981 and 1987, respectively. The Los Angeles County conviction also included a charge of kidnapping for the purpose of committing a sexual offense.

In the 1987 case, Rasmuson was convicted of kidnapping and molesting a 3-year-old boy, the Times reported. Rasmuson abandoned the boy naked in a deserted area miles from his home.

A judge who presided in the case described Rasmuson's actions "as cruel, vicious and callous as conduct can become," the Times reported. Rasmuson was ordered to serve 17 years in prison.

Rasmuson lived in Lompoc, Calif.; Federal Way, Wash.; and Eugene, Ore., before coming to Idaho, according to published news accounts.

Rasmuson has no criminal record in Idaho, according to the state supreme court's data repository.