Police close in on possible location where fugitive dad could be hiding after alleged triple murder

The manhunt for the missing Washington father accused of killing his three daughters has authorities closing in on an area where he is believed to be hiding. 

Law enforcement began zeroing in on the Ingalls Creek and Valley High areas late Monday night in the search for Travis Decker, according to the Chelan County Sheriff's Office (CCSO). 

"Law enforcement is searching for suspect Travis Decker in the area of Ingalls Creek and Valley High as he is believed to potentially be in this area," the sheriff's office posted. "Please secure your homes and vehicles, stay alert, and report any suspicious activity to 911." 

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The area is located approximately 30 miles from Rock Island Campground, where the bodies of Decker's three daughters-Paityn, 9; Evelyn, 8; and Olivia, 5-were discovered three days after they did not return to their mother following a court-approved visit with Decker. 

The new lead comes after the CCSO handed the search for Decker over to federal authorities on Sunday night, with the department remaining in command of the criminal investigation. 

The Chelan County Sheriff's Office did not immediately respond to Fox News Digital's request for comment. 

Washington Gov. Bob Ferguson also deployed the state's national guard to aid law enforcement by providing helicopter transportation as officials continue to comb through the state's dense wooded areas. 

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"We had reached a point where we need to rest our local resources," the sheriff's office said in a statement. "Our command staff continues to be engaged with the search command while we give our teams time off to rest and recuperate and be ready to rejoin the search for, and capture of, the suspect."  

On Monday, officials discovered a "large amount of evidence" from the father's abandoned GMC pickup truck, including blood samples tracing back to Decker and various personal items, according to the sheriff's department. Decker's dog was also found with the vehicle and subsequently placed in the care of the local humane society. 

The announcement regarding the evidence came on the same day the CCSO coroner's office confirmed the three girls' cause of death was suffocation, ultimately ruling the case a homicide. 

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Prosecutors formally charged Decker with aggravated first-degree murder and kidnapping last week. Authorities allege Decker, an experienced survivalist and former member of the U.S. military, killed his three daughters before disappearing into the wilderness.

The girls were found with plastic bags over their heads and bound wrists at a local campground last week.

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Decker's ex-wife, Whitney Decker, 35, told police Decker suffers from mental health issues - including borderline personality disorder - but had always returned the couple's children on time following a visit, according to a CCSO affidavit.  

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Decker is described as standing approximately 5 feet, 8 inches tall and weighing about 190 pounds. Authorities are unsure if Decker is armed, but insist he is considered dangerous. 

If convicted, Decker could face a maximum sentence of life in prison without the possibility of parole.