Will Be ‘Difficult’ to Determine Cause of Death for Remains Believed to Be Travis Decker’s

Human remains believed to be Travis Decker’s, the man accused by police of killing his three young daughters, have been recovered in Washington state. But according to authorities, it could be difficult to determine a cause of death.

Chelan County Sheriff Mike Morrison tells PEOPLE that the remains discovered in a remote wooded area south of Leavenworth, Wash. on Thursday, Sept. 18, were “well decomposed.”

“I’ve heard that the probability of doing it will be difficult,” he says. “Based off the condition of the body. We may never know, according to our coroner. They are still doing the processing, so we’ll see. But unless something’s obvious, it could be difficult for them.”

Morrison says he hopes the medical examiner “can point me in the right direction and let me know, if possible,” but he also realizes it is going to take some time.

“We have our subject matter experts on the ground assessing the remains and seeing what we have as a potential cause of death, if they can determine that at all,” he says.

There is also the question of how long the remains have been there.

“Even the coroner and the medical examiner said they’re not willing to make an estimate yet,” he says. “They want to assess what they have because it really does depend on the environment, conditions, exposure, and other factors that clearly are more in their wheelhouse than mine.”

Decker, 32, was the subject of a massive manhunt after the bodies of his three daughters — Paityn, 9, Evelyn, 8, and Olivia, 5 — were discovered dead in a remote area of the Rock Island Campground in Chelan County, Wash., on June 2 after he failed to return them to his ex-wife following a court-ordered visitation on May 30.

Decker was charged with three counts of first-degree murder and one count of kidnapping in the deaths of the three girls. The U.S Marshals Service offered a $20,000 reward for information leading to his arrest.

The bodies of Decker’s daughters were discovered with plastic bags over their heads, according to a probable cause affidavit previously obtained by PEOPLE. Authorities determined that the three girls had suffocated to death.

On August 6, law enforcement reported DNA profiles matching Decker were found on the bags that were covering the girls’ heads, as well on bloody handprints found on his pickup truck.

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The months-long search for Decker, which included searches in the Blewett Pass area in the Wenatchee Mountains, spanned across the country.

In a press release following the discovery of the human remains this week, the sheriff’s office said they were in contact with the Decker family and “are providing them with support and updates as the investigation proceeds.”