One month after he stunned police by stepping forward to confess to the brutal 1981 killing of an elderly couple in Iowa, a California man pleaded guilty Thursday to two counts of first-degree murder and was sentenced to life in prison.

Jack W. Pursel, 66, entered the guilty pleas during a hearing at the Black Hawk County courthouse in Waterloo. Quoting Bible verses, Pursel said he was taking responsibility for the torture and execution-style shooting deaths of Robert Huntbach and his wife, Goldie, because he had become a born-again Christian and was seeking forgiveness and mercy.

But two of the homicide victims' grandchildren — who testified by giving only their first names, Kevin and Pam, according to statements released by the prosecutor — immediately rejected his plea for forgiveness. Pam said she was disappointed that Iowa does not have the death penalty to punish Pursel for the "sick and cowardly" deaths of her grandparents. Kevin said Pursel would be sentenced to "eternal life in the fire pits of hell" if he had any say in the matter.

Judge Bradley Harris sentenced Pursel to two consecutive sentences of life in prison without the possibility of parole, the mandatory term for first-degree murder in Iowa. The sentencing capped a stunning turn of events in a once high-profile murder case that was never solved and had all but been forgotten.

Pursel, of South Gate, Calif., showed up at the police station out of the blue May 8 to confess to robbing and killing Robert Huntbach, 85, and Goldie, 77, in their home in a working-class neighborhood in Waterloo on Jan. 12, 1981.

Police had interviewed Pursel as one of several persons of interest in the case three decades ago, but he was never charged. Investigators are confident he was the killer because "he provided factual details that were not known publicly and that only the killer would have known," said Black Hawk County Attorney Tom Ferguson.

In a letter to The Associated Press from jail dated May 29, Pursel said he has been stunned by the amount of attention generated by his confession, which he called a statement that is "truly needed by society."

"I wanted this to be as low key as confessing, pleading, judge finding me guilty immediately and sentencing me. I, in my naivete, thought this would be the case until several friends told me to expect this exposure when I turned myself in," he said.

Ferguson said Pursel had previously lived in Waterloo and been in a relationship with a relative of the Huntbachs, the details of which he declined to describe. Pursel robbed and killed the couple while on the run from authorities in California, who wanted him on a rape charge, Ferguson said.

In court Thursday, Ferguson said Pursel tied up and gagged the Huntbachs, possibly smothered them, tortured them with cattle prods and then shot them.

"I don't believe anyone can imagine the sheer fear, horror and emotional anguish that Goldie and Robert experienced as the events unfolded in their home," he said. "To lie helpless, hear shots fired believing your life partner has just been executed, knowing you couldn't do anything and knowing that you are next is indescribable."

He rejected Pursel's claim that he only decided to kill them "when they recognized his voice." He said Pursel's actions seemed vengeful and were intended to inflict pain and heartache on the Huntbachs' family members.

Months after the killings, Pursel was sentenced to a lengthy prison term on three counts of oral copulation with a minor in Los Angeles County. He was released in the 1990s but remains on California's sex offender registry.