Several objects unearthed in the Washington wilderness are under FBI scrutiny to ascertain if they have any connection to Travis Decker, who is accused of killing his three daughters and then fleeing.

The FBI cordoned off extensive areas surrounding the Rock Island Campground on Monday and Tuesday to carry out a thorough search for the elusive father.

Approximately 100 personnel were involved in the search, covering over a million square acres – roughly 247 acres – in difficult terrain amidst the oppressive summer heat to uncover any leads on his location.

In early June, Decker allegedly suffocated his daughters, Paityn, 9, Evelyn, 8, and Olivia, 5, before a custody handover with his ex-wife in Leavenworth, Washington, prompting him to go into hiding.

The girls were discovered inside his deserted truck on June 2 at the Rock Island Campground after he failed to deliver them to their mother on May 30, but Decker was missing.

FBI Seattle Special Agent in Charge W. Mike Herrington said ‘several items’ were recovered which could be of significance.

‘Uncovering this potential evidence underlines the importance of having different teams examine an area multiple times, particularly in such tough scenarios,’ he stated.

The mission was to locate Decker or discover signs that he had been in the area, or otherwise new evidence about the crimes he is accused of committing. 

Search crews, comprised of officers from two sheriff’s offices, the U.S. Marshals Service, two police departments and Central Washington University’s anthropology department, used electronic mapping to document the scope of their search.

They ultimately went beyond their planned perimeter to cover as much ground as they possibly could.

The FBI said while they led this particular search operation, the Chelan County Sheriff’s Office is still the lead on the overall investigation. 

Chelan County Sheriff Mike Morrison insisted investigators ‘have not given up’ on finding him.

‘We understand the frustration, we feel it as well,’ he said at a news conference Monday night.

‘We will not relent, we will not give up until Travis Decker is taken into custody.’

‘This is not going to go away until Travis is located’ whether he is alive or not, the sheriff continued, as he expressed doubts about the former soldier’s ability to survive in the wilderness this long despite his military survival training.

‘He has to be perfect every single day,’ Morrison explained. ‘We just have to be perfect once.’ 

Police said he was also homeless and living out of his car by the time he picked up his three girls from their mother’s house on May 30.

His ex-wife Whitney told police she didn’t believe Decker was dangerous, and that he loved his daughters, with whom he had a ‘good relationship.’ 

A $20,000 reward is on offer for any information leading to Decker’s arrest.

Authorities have warned Decker could be armed and dangerous, and citizens are warned not to approach him.

He is wanted on three counts of first-degree murder and one count of first-degree kidnapping.