Seattle“We got poop samples from Togo!” announced Samuel Wasser, the head of the Center for Conservation Biology at the University of Washington, Seattle, carrying a battered cardboard box into his lab for analysis.

Three larger boxes also arrived that day in February, marked “OPENED FOR KENYA CUSTOMS.” Inside were masses of jumbled vials, each containing a fragment of ivory from illegal shipments of elephant tusks seized by authorities in Mombasa, Kenya.

Wasser was less interested in where the ivory had been seized than in matching DNA in the samples to that in elephant dung—detective work he’s been doing for the past 15 years in an effort to locate the main sources of smuggled ivory.

Wasser’s team reports Thursday in the