backpack," so i knew he was telling me the truth. >> so woloson was arrested and he was forced to provide an additional dna sample. that test left no doubt he was the source of the dna found on susan schumake. prosecutors cannot fathom a reason for susan schumake's murder. they believe woloson saw her walking alone along the dirt path. and he decided to attack her. [ screaming ] it was late in the day. no one heard or saw anything. he left behind his dna. then, took her yellow backpack. stole $10 from her purse, dumped it in the creek, then dropped his bag with the pharmacy prescription in it not far away. >> it's that randomness that's so frightening. she wasn't stalked. she wasn't selected.