By the time he was 16, Joseph Edward Duncan III estimated he had raped 13 younger boys, some at gunpoint, according to Pierce County court records.

At 17, after he was arrested for the rape and torture of a 14-year-old Pierce County boy in 1980, Duncan was deemed to be a sexual psychopath and as an alternative to prison was admitted for treatment to the Sex Offender Program at Western State Hospital. However, he was booted from the program after 22 months when officials learned he was sneaking off the Western campus and having "violent rape fantasies," said Pierce County Prosecutor Gerry Horne. A judge then reinstated his 20-year prison sentence.

"He was a very dangerous young man," Horne said yesterday.

Duncan, now 42, was charged yesterday with two counts of first-degree kidnapping, presumably in connection with the abduction of Shasta Groene, 8, and her brother, Dylan, 9, of Coeur d'Alene, Idaho. The siblings had been missing since May 16, when the bound and bludgeoned bodies of their mother, older brother and mother's boyfriend were found at their rural home near the Idaho town.

Authorities have said they believe Dylan is dead, and that human remains found in Montana this week may be his. They are awaiting DNA test results.

In a handwritten affidavit released yesterday, Kootenai County Sheriff's Sgt. Brad Maskell revealed that Shasta told authorities that she and Dylan had been repeatedly molested by Duncan.

The two-page document also contained new details from the abduction.

The girl recalled being awakened by her mother and watching Duncan tie up her family before she and her brother were placed in a pickup. The children were later transferred to a Jeep and taken to the first of three campsites.

"She knew how she left home," the affidavit said. "Her mother woke her up, went to living room. Man forced family in ligatures."

The affidavit makes no mention of the beating deaths of the girl's family or whether she witnessed the killings.

During a brief court appearance yesterday in Coeur d'Alene, a shackled, unshaven Duncan, wearing a yellow jumpsuit, looked intently at First District Magistrate Judge Scott Wayman and said little, other than to acknowledge that he understood the charges against him.

The pair of first-degree-kidnapping charges do not say who the victims are, but identify them as 8-year-old "S.G." and 9-year-old "D.G" because they are minors. The abductions, charging papers said, occurred during the period of May 15 to July 2, and added that the children were held both in and out of the state of Idaho.

The intent of the crimes, the documents said, was to rape, seriously injure or commit a lewd and lascivious act on a child under 16 years old. Convictions can carry the death penalty or life in prison.

There was a warrant for Duncan for failing to register as a high-risk sex offender and he was facing charges of molesting a 6-year-old boy in Minnesota, where he was released on bail in April, just weeks before the children disappeared. His last-known address was in Fargo, N.D.

A judge who had set Duncan's bail at $15,000, despite prosecutors' request that it be higher, said if he had known Duncan's record, he would have set it high enough that he would not have gone free.

According to Pierce County court records, Duncan, the fourth of five children in a military family, was born in Fort Bragg, N.C. His family moved frequently when he was a youth, and they were living in the Tacoma area when he was a teenager.

When he was admitted to Western State Hospital for the rape of the 14-year-old in 1980, he spoke with therapists about earlier assaults against other children, court records say.

Duncan told therapists that he sexually assaulted a 5-year-old boy when he was 12 years old. When Duncan was 15, he did the same thing to a 9-year-old boy at gunpoint. When he was 16, Duncan told his therapists, he tied up six younger boys and sexually assaulted them.

Duncan, who dropped out of Lakes High School in Lakewood, Pierce County, in 10th grade, estimated that he'd committed about 13 rapes on younger boys by the time he was 16.

Duncan's first recorded brush with the law occurred in 1979 when he was arrested by police after a high-speed chase in a stolen car. He was sent to Dyslin's Boys Ranch for several months. The next year, according to court documents filed in Pierce County Superior Court, Duncan was charged with first-degree rape, first-degree burglary and third-degree statutory rape for the assault on the 14-year-old boy. Police and prosecutors said Duncan broke into a neighbor's house in January 1980 and stole a gun.

He pulled the gun on a boy who was walking to school and forced him into a wooded area, papers say. Duncan made the boy undress and perform a sex act, court documents say. Duncan then walked the boy farther into the woods, sexually assaulted him a second time, and then beat the boy's buttocks with a stick and burned him with a cigarette.

He led the boy back to his clothes and told him to run away.

That night, court records show, Duncan was arrested.

Duncan pleaded guilty to first-degree rape and was ordered to undergo psychological testing at Western State. Mental-health evaluators there said he did not appear to suffer from any clinical mental illnesses, but he was diagnosed with an anti-social personality and as a sexual deviant.

A presentence report on Duncan indicated he had serious sexual-psychopathy issues and would have to be in a controlled environment but also mentioned that his age and appearance could make him a victim were he to be incarcerated in an adult prison.

Reports to the court from his treatment providers at the Sex Offender Program show that at the end of 1980, Duncan's progress was considered good, his therapists wrote. "The amount of change that has occurred in Mr. Duncan has been encouraging. The large amount of self-disclosure is a very positive sign for future success," they wrote.

Duncan admitted to having rape fantasies that he couldn't control and he acknowledged a lonely and solitary childhood. Court documents say Duncan felt isolated and bullied by peers because of his family's constant moves. In addition, he didn't feel wanted at home, he said.

His parents fought constantly until their divorce in 1979, he told his therapists. After that, he felt somewhat displaced by his mother's string of boyfriends and his father rebuffed him when he asked if he could live him.

The victimization of others, he said, was a way of acting out the anger and hostility he felt toward his family.

"It was an outlet for my feelings [of]rejections. One from my mother and one from my father," Duncan wrote in a personal history. By March of 1982, however, his therapists concluded that, after 22 months in the Sex Offender Program, Duncan was no longer trying. "He has chosen not to commit himself to our program techniques," therapists wrote.

The report details two times that Duncan sneaked out of a special facility for extended visits with family, while his parents were sleeping, and prowled the neighborhood. His treatment providers saw the incidents as proof that Duncan was choosing not to control himself.

Duncan was then sent to the state Department of Corrections to serve out his prison term.

Meanwhile, authorities in Idaho yesterday were reviewing video of Shasta and Duncan at a gas and convenience store in Kellogg hours before she was rescued. Kootenai County Sheriff's Capt. Ben Wolfinger said it appeared Shasta was "wanting to be recognized by the patrons there in the store."

"In the small takes I saw out of that surveillance video, she's walking around, stopping, looking right at the faces of the different patrons there," Wolfinger said on ABC's "Good Morning America."

Early Saturday, employees and customers spotted the girl eating breakfast with Duncan in a Denny's restaurant in Coeur d'Alene and summoned police.

Seattle Times staff reporter Mike Carter and Associated Press writers Nicholas K. Geranios and Sarah Cooke contributed to this report.