Purdue University police are searching for a woman who disappeared after visiting her son on campus. Jinhua Liu, 52, was last seen about 5:30 p.m. Sunday at the Purdue Village Apartments. Liu had been staying with her son and daughter-in-law. The couple told police they left her at their apartment but she was not there when they returned at 9:30 p.m. Police say Liu may have been upset at the time she disappeared. No foul play is suspected.