Authorities in Washington State have recovered bones near a campground in the Cascade Mountains during the ongoing manhunt for Travis Decker, a 33-year-old man accused of killing his three daughters.

The discovery was made earlier this week near the Rock Island Campground outside Leavenworth, according to FBI Seattle spokesperson Ted Halla. The bones are being analyzed to confirm whether they are human.

The area is where the bodies of Decker’s daughters—Paityn, 9; Evelyn, 8; and Olivia, 5—were found on June 2. The Chelan County medical examiner determined the girls died by suffocation and ruled their deaths as homicides. Investigators previously reported that DNA found on plastic bags covering the children’s heads matched Decker’s.

Following the discovery of the children, local, state, and federal agencies launched a large-scale search for Decker, who has a military background and outdoor survival experience. His pickup truck was found abandoned in rugged, heavily forested terrain about 150 miles east of Seattle.

Decker faces three counts of first-degree murder and three counts of first-degree kidnapping. A warrant has been issued for his arrest.

Authorities said the case began on May 30, when Decker’s ex-wife reported he had not returned their daughters after a scheduled visit. The report did not initially meet the criteria for an Amber Alert, which requires evidence of imminent danger.

Court filings indicate Decker previously resisted signing a parenting plan that required him to undergo mental health and anger management treatment. Investigators have not identified a motive.

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Chelan County Sheriff Michael Morrison said Monday that about 100 officers and federal agents participated in a two-day search of the area earlier this week. Despite extensive efforts, it remains unclear whether Decker is alive.

“At this time, no conclusive evidence has been found to indicate whether Travis Decker is alive or deceased,” Morrison said in a statement. “We continue to follow every credible lead.”