CANADENSIS, Pa. (AP) -- A rifle-toting man with a mud-covered face who was spotted in Pennsylvania's Pocono Mountains is believed to be the suspect who has spent more than five weeks on the run after a deadly ambush at a state police barracks, officials said Saturday. A woman out for a walk Friday night spotted the man near Pocono Mountain East High School in "a surprise encounter" shortly after 9 p.m., state police Lt. Col. George Bivens said. Investigators said the man was about 15 to 20 feet from the woman, just off the road where she was walking. Police believe the man was Eric Frein, an expert marksman who has eluded capture despite an intense manhunt in the heavily wooded area around his parents' home in Canadensis. "In this particular case, this was a very close-up sighting," Bivens said at a news briefing alongside Gov. Tom Corbett. "The individual that reported it had great detail, and so our investigators believe that this was likely Frein." Frein is charged in the Sept. 12 shooting that killed Cpl. Bryon Dickson and wounded Trooper Alex Douglass, who was transferred from a hospital to a rehabilitation facility on Friday. Frein is described by police as a survivalist with a grudge against law enforcement. Police said they have already found two pipe bombs, one discarded rifle, ammunition, food, clothes and other supplies, along with a journal Bivens previously said contains a "cold-blooded and absolutely chilling account" of the shooting. Authorities said the journal also describes Frein's apparent attempt to flee in an SUV that was later found submerged in a swamp. "I think we've kept a tremendous amount of pressure on him and I think that likely had some bearing on where he's at now, assuming that it is him," Bivens said. Frein attended the high school and state police are keeping school officials informed about any activity that might affect the school. "We have the resources to deal there with anything that could occur in that area," he said. Corbett, a Republican who formerly served two terms as state attorney general, vowed that state police would bring Frein to justice. "We will not rest until we apprehend this individual," he said.