In the hours after his arrest, Eric Frein allegedly told detectives that he ambushed a state police barracks in the Poconos because he wanted to "wake people up" about his concerns over the government.

He also described his killing of a state police corporal as an "assassination," according to an updated list of charges filed in court late Thursday afternoon.

He shot the corporal because "he wanted to make a change" in government and believed "that voting was insufficient to do so, because there was no one worth voting for," investigators wrote in the newly filed court records.

Frein's alleged claims after his arrest resulted in charges of terrorism, a first-degree felony, that have been added to a long list of counts that include murder. The Pike County district attorney has said he will seek the death penalty.

State police investigators also exhumed files from one of Frein's thumb drives that included a letter to his parents written sometime during the 48 days he was on the run in Monroe and Pike Counties, court records stated.

Frein allegedly wrote that "only passing through the crucible of another revolution can get us back the liberties we once had. I do not pretend to know what that revolution will look like or even if it would be successful."

Frein allegedly shot and killed Cpl. Bryon Dickson and seriously wounded Trooper Alex Douglass outside a Pike County police barracks in September.

The 31-year-old self-proclaimed survivalist was caught outside an abandoned airplane hangar in Monroe County on Oct. 30. A preliminary hearing to review the case against him is scheduled for Dec. 9.

"Tension is high at the moment and the time seems right for a spark to ignite a fire in the hearts of men," Frein allegedly wrote to his parents. "What I have done has not been done before and it felt like it was worth a try."