Cao Guifen, 61, a female practitioner working at Weifang Distribution, Storage, and Shipping Company, was hit and killed at around 9 p.m. on April 26, 2002 by Wang Aizhi, the deputy chief of the Nanguan Police Station at Weicheng District, and Yu Mingchun, a member of the guard squadron, driving a police van with no license plate.