Kootenai County Sheriff Deputy Ryan Duncan, right, and William Belton, a private security officer, keep watch over a rural home Sunday near Coeur d'Alene, Idaho, where three people were found murdered on May 16. Authorities uncovered human remains while searching for 9-year-old Dylan Groene, whose sister, Shasta, 8, was found Saturday.

Coeur D’Alene, Idaho ? 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, 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, 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 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 today, when he will be assigned an attorney.

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.”