The manhunt for the Washington father accused of killing his three young daughters has expanded as federal and state law enforcement officials continue to comb through the dense wilderness in search of the military-trained survivalist.Authorities said this week that they are combing through the Teanaway Valley and Blewett Pass areas as the search for Travis Decker continues into its third week, according to the Kittitas County Sheriffs Office."If you have trail cameras or doorbell cameras, please check them for suspicious activity," the department said ina statement. "If you have residences in these areas, check them for anything missing no matter how small or seemingly insignificant."NEW FLYER SHOWS SUSPECTED KILLER DAD MAY HAVE CHANGED APPEARANCE IN WILDERNESS MANHUNT: POLICETheKittitas County Sheriffs Office did not immediately respond to Fox News Digitals request for comment.Decker is wanted for allegedly killing his three daughters Paityn, 9; Evelyn, 8; and Olivia, 5 after their bodies were found near a Washington campsite earlier this month.Authorities began searching for Decker on the evening of May 30 after his ex-wife notified police that he had not returned the couples three children from a court-mandated visitation, according to court documents. Three days later, the girls were discovered near Deckers abandoned vehicle with plastic bags over their heads and their hands bound, police said.ALLEGED KILLER DAD COULD MAKE ONE MISTAKE THAT ENDS MANHUNT, SHERIFF SAYSThe update comes one week after the Chelan County Sheriffs Office (CCSO) announced a group of hikers reported seeing a lone individual who appeared unprepared for the wilderness near Colchuck Lake.When authorities responded to the tip, they "spotted a lone, off-trail hiker from a helicopter," adding the individual "ran from sight as the helicopter passed," CCSO previously said in a press release.The lake is located approximately 40 miles from Blewett Pass and 60 miles from Teanaway Valley by car.A new flyer depicting renderings of ways Decker may have changed his physical appearance was released by authorities on Tuesday. The updated poster includes photos ofDecker with and without facial hair and wearing a baseball hat.SURVIVALISTS GOOGLE SEARCHES REVEAL POSSIBLE ESCAPE PLAN AMID MANHUNT IN DAUGHTERS TRIPLE MURDER: REPORTOfficials also quashed a TikTok video reportedly showing CCSO Sheriff Mike Morrison announcing Deckers arrest after a long standoff."To be clear, Mr. Decker is not in custody and CCSO had no part in making the video," the department wrote in a Facebook post.The U.S. Marshals Service has taken on the role of lead agency in the hunt for Decker, who is a former member of the military with extensive experience in wilderness survival. The Washington National Guard is also assisting local law enforcement with aerial search efforts and surveillance.Officials warn that Decker is considered armed and dangerous but do not have reason to believe he is a threat to public safety.The U.S. Marshals Service is offering a $20,000 reward for information leading to Deckers arrest. He is charged with three counts of aggravated first-degree murder and kidnapping.