Male Blood Found at Campsite Where 3 Sisters Were Killed — and Authorities Believe It May Be Their Father's

Male blood was found at the remote Washington campsite where three sisters were killed, investigators revealed on Monday — offering a chilling new detail as their father, the sole suspect, remains missing. 

In a news release shared with PEOPLE, the Chelan County Sheriff’s Office confirmed that one blood sample recovered from Rock Island Campground — where the bodies of Paityn, 9, Evelyn, 8, and Olivia, 5, were discovered — was identified as male. 

A second sample tested as non-human, the office said.

Authorities believe the girls were killed during a court-ordered visitation with their father, 39-year-old Travis Decker. The sisters were reported missing on May 30 after Decker failed to return them to their mother in Wenatchee. 

On June 2, their bodies were discovered in a tent near Decker’s abandoned white pickup truck, PEOPLE previously reported.

According to the same release, two bloody handprints were found on the truck’s tailgate. DNA and fingerprint analysis is ongoing, the department said.

Decker’s dog was also found near the scene, and has since been turned over to the local humane society, per the sheriff’s office.

The investigation remains active and ongoing across rugged, remote terrain. Federal officials have joined in the search, though the sheriff’s office continues to lead the criminal investigation. Search efforts have centered on areas including Ingalls Creek and Valley High.

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Decker, a former Army soldier with survivalist experience, is charged with three counts of first-degree murder, kidnapping, custodial interference and unlawful flight to avoid prosecution. 

Authorities believe Decker may have been attempting to flee to Canada.

According to a U.S. Marshals affidavit shared with PEOPLE, investigators discovered that he had allegedly searched online for “how to relocate to Canada” and visited a Canadian government employment site in the days leading up to the killings.

Given Decker’s military background and survival training, officials have also speculated that he could be traveling through remote terrain, possibly using trails near the border.

Authorities say they believe the male blood found at the scene likely belongs to Decker himself. The origin of the non-human sample is still being confirmed.

Officials continue to warn that Decker may be armed and dangerous, and anyone with information is urged to contact Chelan County Dispatch or dial 911.