Frein, 31, is accused of ambushing state police in early September, killing one and wounding another. Since then, police say he has been hiding in the woods of the Pocono Mountains.
"Overnight we had a sighting for which we are assigning a high level of credibility," Lt. Col. George Bivens of the Pennsylvania State Police said today. "It was reported in the area of the Pocono Mountain East High School. The individual's description was consistent with Frein and he was observed carrying a rifle."
The woman who saw the man said that his face was "covered with mud," so a positive identification could not be made, but she was about 15 to 20 feet from him.
After learning of the new possible sighting, police shifted the search area, he said.
"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 Pocono East High School and worked at Camp Minsi, which is also in the vicinity, Bevins said.
Investigators are also analyzing blood found on the back porch of a home near Cresco. They are not sure if the blood is related to the investigation and expect the test results to come back late this evening.
State police say the weather is working in their favor, because as leaves continue to fall, there is a better aerial view from choppers and planes.
Police have been searching the woods, focusing on the border of Pike and Monroe counties, since after the shooting at the Blooming Grove police barracks on Sept. 12.
Frein, from nearby Canadensis, has been spotted several times, but always evaded police capture because of the thick terrain. He's a self-trained survivalist and war reenactor who focused on Eastern European militaries and weapons.
Police found Frein's Jeep in a swamp shortly after the shooting. They have also found two pipe bombs, an AK-47, food, ammunition, clothing and other supplies in the search.