CANADENSIS, Pa. (AP) -- The suspect in the deadly ambush at a state police barracks in a remote part of northeastern Pennsylvania remained at large for an eighth day Saturday as police appeared to have narrowed their search, largely shutting down the area where he lived with his parents but leaving neighbors with few answers about what's going on just outside their front doors. With a helicopter flying overhead, law enforcement officers wearing bulletproof vests and armed with rifles continued their hunt for Eric Frein, 31, now on the FBI's Most Wanted list. "Our troopers are determined to find him and bring him to justice," state police spokeswoman Maria Finn said. Police released few details about their search of the heavily wooded community in the Pocono Mountains, saying only that they were exercising extreme caution. Late Saturday, authorities lifted a shelter in place order but urged residents returning home to use caution and to stay out of the dense, boggy woodlands where the search was underway. Authorities say Frein used a high-powered rifle to open fire from the woods near a state police barracks on Sept. 12, killing Cpl. Bryon Dickson -- a married ex-Marine with two sons -- and wounding Trooper Alex Douglass. Frein -- described by authorities as a self-taught survivalist with a grudge against police -- has been on the run ever since, authorities said. But some who know him said he has not always played the loner, and the reason for his hatred of police remained a mystery. Frein belonged to the rifle team at Pocono Mountain High School, and as an adult joined a group that performed military re-enactments based on Cold War battles in Eastern Europe. He even played a small role in a 2007 movie about a concentration camp survivor -- earning him a mention in the movie database IMDb -- and helped with props and historical references on a documentary about World War I. "He was a very friendly guy to me," said Jeremy Hornbaker, who hired him for the documentary. "We left on very good terms." Frein's father, retired Army Maj. E. Michael Frein, told police that he had taught his son to shoot. He "doesn't miss," the father told state police during a search of the family home, when he also disclosed that an AK-47 and a .308 rifle with a scope were missing. A copy of the book, "Sniper Training and Employment," was found in his bedroom. It was Frein's abandoned vehicle that led police to their door. The green Jeep, registered to his parents, was found partly submerged in a local pond days after the shooting. Shell casings that matched the state police ambush were still inside, as were Frein's driver's license, Social Security card, camouflage paint and military gear. Lars Prillaman, who manages a small farm in West Virginia, knew Frein briefly from their time as military re-enactors. He said Frein was "a different person eight years ago." Frein had for a time attended nearby East Stroudsburg University and held a number of jobs over the years but never any for very long, authorities said. A week after the killing, they had not said anything about what may have led to his hatred of police. Roger Smith, the owner of Smitty's Sporting Goods in Canadensis, told The Scranton Times-Tribune that about a year ago he noticed Frein loitering outside of his store. Frein briefly stepped into the store several times that day but did not buy anything. When he asked him what he was dong, Frein motioned to a police car that just drove by and said, "Me and those guys don't get along," the store owner said. Frein's only known legal problems stemmed from the 2004 theft of some vendor items at a World War II re-enactment in Odessa, New York. He failed to show for his trial, and was arrested in Pennsylvania as a fugitive from justice. In the years that followed, from 2004 to 2013, he bought four firearms at Dunkelberger's Sports Outfitter in Stroudsburg, store owner Jere Dunkelberger told The Associated Press. He did not know what type of weapons they were. On Frein's MySpace page, a photo appears to show him standing in front of the Serbian Orthodox Church in Belgrade. Frein played the part of a Serbian soldier in his re-enactments and the FBI said he had claimed to have studied Russian and Serbian and to have "fought with Serbians in Africa." The FBI's Most Wanted poster describes him as 6-foot-1, 165 pounds. State police said he apparently cut his hair into a wide Mohawk in preparation for the attack. He was also described as a heavy smoker.