Authorities said Monday they found human remains during their search for a missing 9-year-old boy whose sister was found days earlier at a Denny's restaurant with a registered sex offender.

Sheriff Rocky Watson said the remains were found in western Montana and would be sent to an FBI laboratory for DNA analysis. He did not say whether the remains were believed to be those of Dylan Groene (search), and declined to answer questions.

Officials said previously there was little hope Dylan was still alive. The DNA analysis was expected to take three days.

Dylan's 8-year-old sister, Shasta, was found Saturday with Joseph Edward Duncan III (search), more than six weeks after the children disappeared from the home where their mother, her boyfriend and an older brother were bludgeoned to death.

Authorities planned to charge Duncan, 42, of Fargo, N.D., with kidnapping and being a fugitive from justice, and have said more charges were possible; federal and local authorities searched Duncan's Fargo (search) apartment, but police did not know if authorities took any items or if anything resulted from the search. A judge ruled Monday there was probable cause to keep Duncan in jail until an initial court appearance Tuesday, when he will be assigned an attorney.

With Duncan refusing to talk, authorities have been relying on statements from Shasta, physical evidence in Duncan's Jeep and tips from the public as they searched for Dylan.

Watson said the remains were found in western Montana, but did not elaborate about the site or say what led investigators there.

"Investigators continue to follow all of the other leads in this complex case," Watson said. "This case continues to be the number one priority for all agencies involved."

About 60 investigators were involved in the case. Sheriff's Capt. Ben Wolfinger said earlier Monday that Shasta had provided helpful information, but declined to say what the girl was telling officers.

"It's a slow process with Shasta," Wolfinger said Monday. "We're taking that very slowly."

Officials have said they believe Dylan was still alive when he and Shasta disappeared. Investigators said they had received some 100 tips about Duncan and the red Jeep Cherokee he was driving since photos were released Saturday.

Based on those tips and other information, authorities believe Duncan and Shasta remained in the Northwest the entire time, Wolfinger said. He would not say if there was any evidence others were accompanying Duncan.

The girl's father, Steve Groene, said Sunday he was told not to ask the girl questions about her ordeal. He said Shasta was doing well and had been watching animated movies and had a vanilla shake and pancakes for breakfast.

He thanked those who helped find his daughter, and held out hope that Dylan would also be found.

"Shasta is doing very well and we all are very hopeful that Dylan will come home safely," he said.

The children were declared missing when authorities arrived at their home May 16 and found the bound and bludgeoned bodies of their mother, Brenda Groene, 40, brother Slade Groene, 13, and their mother's boyfriend, Mark McKenzie, 37.

Officials have not said why they believe the Groene family was targeted. Steve Groene said he had never heard of Duncan before Saturday.

The children's faces had been posted across the region, shown repeatedly on television and placed on billboards. Employees and customers at the Denny's restaurant said they recognized Shasta almost immediately when she came in around 2 a.m. Saturday with Duncan, and several called 911.

Duncan, who was raised in Tacoma, Wash., had spent more than a decade in prison for sexually assaulting a 14-year-old boy at gunpoint and was a fugitive at the time of his arrest for allegedly molesting a 6-year-old boy in Minnesota.

A registered high-risk sex offender, Duncan was released on $15,000 bail earlier this year after being charged with molesting the boy. Police in Fargo had been looking for Duncan since May, when he failed to check in with a probation agent.

Days before the children disappeared, a message appeared on a Web site that officials said Duncan maintained. It said: "My intent is to harm society as much as I can, then die."