Chimera by Ken Goddard
U.S. Fish and Wildlife Special Agent Gedimin Bulatt is in Thailand for a conference when a party of illegal hunters are discovered by local forestry rangers, leaving four rangers dead and his friend and fellow officer gravely wounded. This begins Bulatt's search for the members of that illegal hunting party culminating in a climax in the wilderness of Washington State, where a rogue geneticist has created creatures resembling mammoths to be killed by these rich men. Bulatt finds himself targeted, while he and his companion seek to gain evidence needed to arrest the illegal hunters and their ruthless guides.