Male blood was found at the remote Washington campsite where three young sisters were killed, investigators revealed Monday—adding a disturbing new detail as their father, the only suspect, remains missing.

According to the Chelan County Sheriff’s Office per PEOPLE, one of the blood samples found at Rock Island Campground, where the bodies of Paityn, 9, Evelyn, 8, and Olivia, 5, were discovered, belonged to a male. Another sample was determined to be non-human. Continues…