OKLAHOMA CITY (AP) -- Prosecutors in northern California have decided not to seek criminal charges against a Rice University student found unharmed after disappearing nine months ago.

University of California-Berkeley campus police arrested Matthew Wilson after finding him in a classroom after school hours with a laptop they believed was stolen. Wilson was taken into custody but was transferred to a San Francisco Bay-area mental hospital and placed on suicide watch.

Alameda County, Calif., prosecutors said the only evidence that could have been used to charge Wilson were a pair of scissors he had with him that apparently were university property. Officials were unable to determine the laptop was stolen.

Wilson, who is from Oklahoma, was enrolled at Rice University in Houston but was last seen Dec. 15 before he was to take his finals.

Rice and his family offered a combined $20,000 reward for information on his whereabouts. Crime Stoppers of Houston pitched in another $5,000 for information that would've led to felony charges.