ST. LOUIS (AP) — The mother of a 26-year-old researcher mauled by chimpanzees in South Africa says her son has been passionate about chimps for years and knew the risks involved in studying primates.

Andrew Oberle, a graduate student at the University of Texas at San Antonio, was in critical condition Friday after undergoing surgery near Johannesburg. Officials say Oberle was giving a lecture Thursday at the Jane Goodall Institute Chimpanzee Eden when two chimpanzees pulled him under a fence. Officials say Oberle had several severe bite wounds.