Police are hoping that tourists flocking to the “American Alps” this summer will help them to find a murder suspect accused of killing his three daughters.

Detectives have been searching for Travis Decker after his children Olivia, five, Evelyn, eight, and Paityn, nine, were found dead on June 2.

He has been accused of suffocating his daughters with plastic bags after picking them up from their mother for what should have been a three-hour joint custody visit on May 30.

The children were found at an abandoned campsite in the Cascades, a picturesque mountain range in Washington state which attracts tens of thousands of visitors annually.

The search for Mr Decker, an army veteran who has wilderness survival skills, has been complicated by difficult terrain.

A search of the area using drones, a white water team and GoPro cameras has so far been unsuccessful.

However, officials hope tourists descending on the area could help them catch the suspect.

“It may work in our favour, now that we have that many people out there just saturating that part of the county with camping, hiking and other recreating,” Chelan County sheriff Mike Morrison told CNN.

He added: “This is typically how cases like this are brought to an end – is that we have someone that remained observant, saw something, reported it.”

‘Eventually, luck runs out’

Officers found Mr Decker’s truck around 100 yards from where his daughters’ bodies were discovered at the Rock Island Campground, suggesting he fled on foot. Cable ties and plastic bags were also found in the area, police said.

A bloody fingerprint was discovered on the truck’s tailgate, while blood at the scene matched a DNA profile believed to be Mr Decker’s.

Police are now expanding their search to Icicle Creek, which runs through the Cascades, after its waters began to recede.

“We’re not going to glorify his abilities. We don’t think that he’s some kind of special forces guru,” Mr Morrison said. He added: “He could get lucky at times, and eventually, luck runs out.”

On June 10, authorities in Washington said there had been a suspected sighting of Mr Decker near a remote lake in a popular backpacking area in the Cascade Range.

Tracking teams followed up on a tip from hikers who reported seeing a lone walker who appeared to be ill-prepared for the conditions.