Disturbing New Details Revealed About Killings of Travis Decker’s Daughters, as Police Give Update on Search

New details have emerged in the case of Travis Decker, the Washington state fugitive accused of killing his three daughters.

Decker, a 32-year-old U.S. Army veteran, went missing on May 30 during a court-approved visit with his daughters, Paityn, 9, Evelyn, 8, and Olivia, 5. When he failed to return the girls to their mother, Whitney Decker, at the scheduled 8 p.m. drop-off in Wenatchee, Wash., concern escalated quickly.

Whitney reported the girls missing around 9:30 p.m., sparking a three-day search that ended in tragedy: the children were found dead near Travis’ abandoned pickup truck at the remote Rock Island Campground in Chelan County on June 2. Travis, meanwhile, remained at large.

He is wanted on first-degree murder and kidnapping charges and has not been apprehended nearly three months after the search began.

Each girl was discovered with plastic bags over her head, and at least one was restrained with zip ties, according to an affidavit previously obtained by PEOPLE. In an updated press release on Tuesday, Aug. 19, the Chelan County Sheriff’s Office provided additional information about the condition in which the sisters were found.

“Two of the victims each had two separate bags over their heads, and the third victim had three separate bags over her head,” the release states. “In addition, several cable ties were located on the ground in the immediate area of the bodies.”

A medical examiner determined that all three sisters died of asphyxiation, and their deaths were ruled homicides.

The Chelan County Sheriff’s Office confirmed Tuesday that Travis remains the sole suspect, citing DNA evidence allegedly linking him to all the plastic bags covering his daughters’ heads and one of the zip ties found at the scene.

“The completion of this DNA analysis provides additional evidence that indicates Travis Decker is the only suspect involved in committing these homicides,” the sheriff’s office said.

Investigators previously confirmed that the DNA in blood found on the tailgate of Travis’ truck matched the profile they believe is his.

Travis has been the subject of an intensive manhunt. Authorities have noted that the military veteran is highly skilled in wilderness survival and have suggested he may have fled to Canada after reportedly searching “how to relocate to Canada” online, according to a U.S. Marshals Service affidavit obtained by PEOPLE.

There have been two unconfirmed sightings of Decker: one on June 10 near Highway 97 in Washington State and another on July 5 in the Bear Creek area of the Sawtooth National Forest in Idaho. Officials later said neither sighting was confirmed.

“At this time, we do not have any evidence to suggest Travis Decker is either alive or deceased,” the sheriff’s office stated.

The U.S. Marshals Service has offered a $20,000 reward for information leading to his arrest.