National Guard deployed in manhunt for survivalist accused of killing his three young daughters

The search has intensified for a Washington state survivalist who has been on the run from authorities for more than a week after he allegedly killed his three young daughters.

Washington Gov. Bob Ferguson activated the state's National Guard late Friday to assist in the manhunt for Travis Caleb Decker, 32, who disappeared after he failed to return his children following a scheduled visitation.

Separately, police said that more than 100 officers are now searching for Decker, with more than 500 tips coming in from the public as police said their focus on the fugitive has narrowed. 

"At the request of the Chelan County Sheriff's Office, we will be providing helicopter transportation for law enforcement as they search in remote areas," Ferguson wrote on X.

AUTHORITIES RELEASE NEW DOORBELL CAMERA VIDEO OF SUSPECT WHO ALLEGEDLY KIDNAPPED, MURDERED THREE DAUGHTERS

"As a parent, my heart goes out to Paityn, Evelyn and Olivia's mom, Whitney, and all those who love them. The brutal murder of these young children has shocked our state. I'm committed to supporting law enforcement as they seek justice for Paityn, Evelyn and Olivia."

The girls were discovered on Monday with plastic bags over their heads and bound wrists at a campground in Chelan County, approximately 75 to 100 yards from Decker's abandoned truck. They are believed to have died from asphyxiation.

Authorities said that new surveillance video, photos and tips from the public are continuously surfacing, which aid in decision-making to find Decker.

Decker spent time in the military and is an avid outdoorsman, according to authorities. He did not have legal custody of the girls at the time.

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"Despite the many challenges faced and the complex ongoing murder investigation, morale and effort remains extremely high within staff at the Command Post," the Chelan County Sheriff's Office said in a press release.

"Out of an abundance of caution, we have been given notice to, and are working in conjunction with our surrounding counties in the event Mr. Decker moves through the forest into their jurisdiction. Additionally, the more agencies we can get involved, and the more the public remains vigilant, the better opportunity for success in the capture of Mr. Decker."

Chelan County Sheriff Mike Morrison released a new photo on Thursday showing Decker's tattoos and said that search warrants had generated leads. He urged homeowners and people with mountain cabins to lock their doors - including to sheds and outbuildings, leave their blinds open and turn on outdoor lighting.

The children were ages 5, 8 and 9. Decker's ex-wife, Whitney Decker, 35, told police Monday that he had failed to bring the girls back to her after a Friday visit under the terms of their court-ordered parenting plan, according to court documents. 

Morrison said authorities had not identified a motive. "Clearly, it's not the decision of a sound mind," he said.

Travis Decker was limited to visiting the girls every other weekend - and not overnight - according to a court-ordered parenting plan that he did not sign. When he did not bring the girls back by an 8 p.m. curfew Friday, his ex tried calling him - but her attempts went straight to voicemail, according to a Chelan County police affidavit.

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She told investigators that he had never missed the deadline to return their children before, but warned that he has mental health issues, including borderline personality disorder.

He is homeless and splits his time between motels and campgrounds, according to the affidavit.

WATCH: New footage released by authorities shows murder suspect Travis Decker

Decker drives a 2017 white GMC Sierra with the Washington license plate D20165C, according to authorities. License plate scanners picked up the vehicle heading north over the Wenatchee Bridge on Friday at around 5:40 p.m. He did not show up for work Monday, according to the affidavit.

A Chelan County sheriff's deputy found the truck around 4 p.m. on Monday at the Rock Island Campground in Leavenworth, Washington. They found all three girls' bodies between 75 and 100 yards away, down an embankment, according to court documents.

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Each one had a plastic bag over her head, and "their wrists were also zip-tied or showed signs of being zip-tied," according to the affidavit. Deputies found two bloody handprints on the pickup's tailgate. 

Decker's whereabouts remain unknown, and he is charged with three counts each of aggravated first-degree murder and kidnapping. 

He is described as standing about 5 feet, 8 inches tall and weighing 190 pounds with black hair and brown eyes. He has tattoos on both arms and was recently photographed with a goatee and mustache. 

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It is unknown whether he is armed, but authorities say he should be considered dangerous.

The Chelan County Sheriff's Office is advising anyone who sees Decker to avoid approaching him and call 911 immediately. He faces a maximum of life in prison without the possibility of parole.

Authorities are offering a reward of up to $20,000 for information leading to his arrest.

Fox News' Christina Shaw contributed to this report.