Inside, investigators found shell casings matching those found at barracks as well as Frein's driver's license, camouflage face paint, two empty rifle cases and military gear. Using dogs, thermal imaging technology and other tools, law enforcement officials combed miles of forest as they hunted for Frein, whom they called an experienced survivalist at home in the woods. Trackers found items they believe Frein hid or abandoned in the woods — including soiled diapers, empty packs of Serbian cigarettes, an AK-47-style assault rifle and ammunition and two pipe bombs that were functional and capable of causing significant damage. Police found a U.S.