Authorities reveal disturbing new details from crime scene where 3 girls were killed

The search for Decker, 32, has lasted nearly three months.

This story contains information that may be disturbing to some readers.

As the search for Travis Decker -- the dad accused of killing his three daughters -- has almost reached the three-month mark, officials are revealing disturbing new details about the crime scene and the evidence that they say indicates he is the sole suspect.

Paityn Decker, 9; Evelyn Decker, 8; and Olivia Decker, 5, were found dead near the Rock Island Campground in Chelan County, Washington, on June 2, after they left home for a planned visit with their father on May 30, according to police.

Court documents obtained by ABC News in June revealed there were plastic bags over the heads of each girl and their wrists were zip-tied, but a new press release from officials on Monday provided new details about how the children were found.

"Two of the victims each had two separate bags over their heads and the third victim had three separate bags over their head," officials said.

In addition to the plastic bags, "several cable ties were located on the ground in the immediate area of the bodies," officials said.

Authorities collected the plastic bags and the cable ties and submitted the items to the Washington State Crime Lab for DNA analysis, officials said.

On Aug. 6, the crime lab reported that the "DNA profiles matching Travis Decker were found on the plastic bags" and on the cable ties, confirming to officials that he is the sole suspect.

"The completion of this DNA analysis provides additional evidence that indicates Travis Decker is the only suspect involved in committing these homicides," officials said.

DNA matching the three daughters was also located on the plastic bags, officials said. On June 9, an autopsy determined the girls' cause of death to be suffocation, according to the sheriff's office.

In July, officials also said that the bloody handprints located on the tailgate of Decker's vehicle -- which was discovered near the girls' bodies -- also matched the father's DNA profile.

The new announcement from officials comes a month after they said they were scaling back search efforts to find Decker due to a "reduced footprint" and a "decrease in leads and tips."

The sheriff's office confirmed on Monday that Decker's whereabouts remain unknown and that they "do not have any evidence to suggest Travis Decker is either alive or deceased."

The Chelan County Sheriff's Office said it is continuing to work with local, state and federal law enforcement partners to "coordinate continued search efforts."

In July, Chelan County Sheriff Mike Morrison told ABC News that officials remain "hopeful" they will find Decker but are aware this hunt could be a "long haul."

"We could be in a fight for five years, 10 years, 20 years. I certainly hope we're looking at a couple weeks and it closes out, but it could be a long time and we are committed to staying with it," Morrison told ABC News.

The U.S. Marshals Service is still offering a reward of up to $20,000 for information leading directly to Decker's arrest.

Officials said anyone who sees Decker or knows of his whereabouts should call 911 immediately and not contact or approach him. He is currently wanted for three counts of first-degree murder and three counts of kidnapping, officials said.

Decker is considered armed and dangerous, officials said.

For a timeline of what we know about the murder of the three sisters, click here.