Authorities in Pennsylvania who are searching for the man who fatally shot one officer and injured another last weekend have found a rifle that they believe longs to him. 

Eric Frein, 31, opened fire at the Blooming Grove police barracks on Sep. 12, killing Cpl. Bryon Dickson and injuring Trooper Alex Douglass. According to the Associated Press, the discovery of an AK-47 assault rifle and ammunition on Sunday has police convinced they're close to locating him. State Police Lt. Col. George Bivens told the Associated Press that Frein may have been planning the attack for years: 

Investigators said they believe the suspect they describe as a self-taught survivalist had been planning a confrontation with law enforcement for months, if not years.

Bivens added that police are "pushing [Frein] hard," and that he's certain an arrest will take place soon. Frein, who's currently on the FBI's Most Wanted List, is believed to be armed and dangerous. 

[via The Associated Press]