For months after three women on a sightseeing trip were abducted and killed outside Yosemite National Park this year, Cary Stayner kept to his usual rounds as a handyman at the mountain lodge near where they were last seen alive. He reported to work every day, hardly noticed and never feared. FBI agents had questioned him about the killings but ruled him out as a suspect.

Now, in a startling twist to a grisly crime story unfolding at one of the country's premier tourist destinations, they say that was a mistake.

Another woman, a naturalist working in Yosemite's majestic forests, was found dead outside her cabin last week, the victim of an attack as savage as the others. She had been decapitated. And law enforcement officials investigating the four slayings say they believe that Stayner may be responsible for all of them.

He has been arrested and charged in the killing of the naturalist, 26-year-old Joie Ruth Armstrong, and the FBI says that it considers him a prime suspect in the deaths of the other women even though several former convicts have been in custody for months in connection with those crimes.

In an affidavit filed today in Sacramento, the FBI said that the 37-year-old Northern California man had confessed to killing Armstrong, with details known only to law officers. Investigators said he became a suspect after his sport utility vehicle was seen near Armstrong's cabin shortly after she disappeared Wednesday evening. Authorities initially questioned Stayner about Armstrong's slaying on Thursday. They searched his vehicle and his backpack but let him go after he denied involvement in the killing.

Investigators apparently found evidence linking Stayner to the other killings during a search of the room he rented above the Cedar Lodge's restaurant, but they have not disclosed what that evidence is. Late tonight, the Associated Press quoted law enforcement sources as saying Stayner also had confessed to killing the three sightseers, but the FBI declined to comment on the report.

Stayner's arrest has relieved residents and tourists alike around the huge national park, which lies 150 miles east of San Francisco and rarely has been a setting for violent crimes among its 4 million annual visitors. But the arrest is raising questions about the massive federal and local investigation into the other three killings.

Stayner was apprehended at a nudist resort near Sacramento on Saturday, where someone recognized him from news reports and called police. Until then, law enforcement officials had seemed on the verge of charging a loose-knit band of men who had a history of drug abuse, domestic violence and sexual assault charges.

FBI officials declined to answer questions about the investigation today, but at a Sunday news conference announcing Stayner's arrest, James Maddock, the special agent in charge of the bureau's Sacramento office, expressed a note of regret that the case had not been solved sooner.

"I have asked myself whether we could have done anything differently that might have prevented the murder of Joie Armstrong," he said. "I have struggled with that issue for the last 24 hours and continue to do so. Nevertheless . . . I am confident we have done everything that reasonably could have been done."

Maddock also said that as yet investigators had not established a connection between Stayner and the other men they have been holding since the spring on parole violations. Authorities say they are not certain that Stayner acted alone--some still doubt that he could have abducted, killed and dumped the bodies of three women by himself--but Maddock said he is confident all possible suspects are behind bars.

News of Stayner's arrest, meanwhile, shocked employees at the Cedar Lodge who had long watched him work quietly and diligently at his job, even after the slayings of Carole Sund, her 15-year-old daughter Juli and a teenage friend visiting from Argentina, Silvina Pelosso. That trio, who had come to Yosemite for a weekend of hiking, was last seen alive in the parking lot outside the Cedar Lodge restaurant. Stayner was known to eat most of his meals there, often alone.

He had worked at the lodge for most of the last two years as a handyman, although people at the motel said he was laid off for a few months this winter because there was no work for him to do. He was rehired March 18, about the same time the bodies of the three women were found. Investigators say that one of them had her throat deeply slit in much the same manner as Armstrong. Two bodies were found in the trunk of a burned-out rental car; the other was hidden near a rural highway.

At that time Stayner, like many people in the remote area, was questioned about the deaths.

"He has been a fixture here for quite a while," Lisa Hansel, a manager at the restaurant, said today. "You would never suspect him in something like this. He was clean-cut, almost in a military way. He mostly just seemed to keep to himself and to do his job. I never heard anyone complaining about him."

Stayner, whose only previous arrests have been for marijuana possession, is from Merced, a small town about 60 miles west of Yosemite. His family's name is well-known to many in California because it was involved in one of the most highly publicized child-abduction cases in recent state history.

Stayner's younger brother, Steven, was kidnapped from a shopping mall in 1972 and held captive and sexually abused for seven years until he was reunited with his family. The sensational crime became the subject of a television miniseries. Steven Stayner later died in a motorcycle accident.

Special correspondent Cassie Stern contributed to this report.

Yosemite Slayings

Cary Stayner, brother of the highly publicized kidnapping victim Steven Stayner, confessed to beheading a naturalist in Yosemite and is suspected in three other slayings in the area.

March 19: Bodies of Silvina Pelosso and Carole Sund discovered in trunk of burned-out rental car near Long Barn. They and Juli Sund were last seen in El Portal.

March 25: Juli Sund's body found on hillside near Don Pedro Reservoir.

Thursday: Joie Armstrong's decapitated body found near her home in El Portal.

Saturday: Cary Stayner, of El Portal, arrested at a nudist resort near Sacramento.

1972: The suspect's brother, Steven Stayner, was abducted from a Merced street at age 7 and remained missing for seven years.

SOURCE: Staff reports