NAIROBI, Kenya (AP) — Kenya police and officials say an American investigator into the illegal ivory and rhino horn trade has been found stabbed to death in his house in the Karen neighborhood.

Nicolas Kamwende, head of criminal investigations in Nairobi, said Monday that a family member went to Esmond Bradely Martin's house Sunday to check on him after he did not respond to phone calls and found the body on a bed with a stab wound to the neck.

Conservationist Paula Kahumbu said Martin led investigations into the illegal trade of elephant ivory and rhino horn that threatens the two species with extinction. Kahumbu said he was at the forefront of exposing ivory traffickers in the U.S., Congo, Vietnam, Nigeria, Angola, China and recently Myanmar.