A staffer at Shawano County Library found the backpack Monday and turned it over to police. Prosecutors say there were three small bags of meth inside, along with a martial arts weapon known as nunchucks.
The 31-year-old suspect showed up at the police department later in the day. Court documents say he told police he had taken the drugs from his ex-girlfriend because he was investigating her drug-dealing, and that he had the nunchucks to protect himself from her.
He was arrested for drug possession.