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

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." 

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. 

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. 

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.

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.  

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.