Officials believe they have located Travis Decker, a former soldier wanted for the murders of his three daughters, near a secluded mountain lake in Washington state, USA. This information follows a tip-off from hikers who reported seeing an individual who seemed inadequately equipped for the environment.

The Chelan County Sheriff’s office announced on Facebook that tracking teams rushed to the site, and a helicopter unit observed a hiker near Colchuk Lake, a well-known hiking destination in the Cascade Range referred to as The Enchantments.

The off-trail hiker ran from sight as the helicopter passed, the sheriff’s office said.

Teams later found a trail, and K-9 teams tracked the person to the area of the Ingalls Creek Trailhead, south of Leavenworth.

Authorities did not specify the exact time they spotted the individual, but on Monday night, they warned residents in the Ingalls Creek and the Valleyhi area to secure their properties and remain vigilant for Decker.

Decker, 32, has been the target of a large manhunt ever since June 2, when a sheriff’s deputy found his truck and the bodies of his three daughters — nine-year-old Paityn Decker, eight-year-old Evelyn Decker and five-year-old Olivia Decker — at a campground outside Leavenworth.

He had failed to return the girls to their mother’s home in Wenatchee, about 160km east of Seattle, following a scheduled visit three days earlier.

Decker was an infantryman in the US Army from March 2013 to July 2021 and deployed to Afghanistan for four months in 2014.

He has training in navigation, survival and other skills, authorities said.

He once spent more than two months living in the backwoods off the grid.

Officials with an array of state and federal agencies have searched hundreds of square miles, much of it mountainous and remote, by land, water and air.

The US Marshals Service was offering a reward of up to $US20,000 ($30,000) for information leading to his capture.

Last September, his ex-wife, Whitney Decker, wrote in a petition to modify their parenting plan that his mental health issues had worsened and that he had become increasingly unstable, often living out of his truck.

She sought to restrict him from having overnight visits with their daughters until he found housing.

An autopsy on Friday determined the cause of death to be suffocation, the sheriff’s office said.

The girls had been bound with zip ties and had plastic bags placed over their heads.