About 23,000 African elephants were killed by poachers last year, and the death count is on the rise. Alarmed by the loss, University of Washington conservation biologist Samuel Wasser decided to fight back. He and his colleagues have painstakingly created a DNA-based map of the distribution of African elephants. Then, borrowing a few tricks from forensic dentistry, he devised a method for extracting DNA from seized ivory, which can be compared with his map to pinpoint exactly where elephants are being killed. Without that information, nobody can be held responsible for protecting the animals.

“In the past,” Wasser says, “authorities could track shipments, but they never knew where the ivory came from,” making it impossible to hold wildlife officers accountable. Until confronted with hard evidence, “countries tend to deny they have a poaching problem,” he says. For example, analysis showed that the largest ivory seizure in history—a 6.5-ton cache representing ivory from up to 6,500 elephants, recovered in Singapore in 2002—came primarily from Zambia. “Until we had the data,” he explains, “they were saying, ‘The shipment may have come from here, but it wasn’t our elephants.’ When we were finally able to show that it was their elephants, all of a sudden things started to turn around.” After the DNA results came out, the Zambian government fired its director of wildlife and imposed harsher sentences for ivory traffickers.

Still, even huge seizures are just the tip of the iceberg, Wasser says. After the initial success of the ivory ban almost 20 years ago, Western nations considered the problem solved and withdrew funding a few years later, leaving poorer countries to fight poachers on their own. In response, the ivory trade has taken off. China and Japan are the largest markets, and the price has shot up from $45 a pound in the late 1990s to $90 in 2004 and up to $385 in March 2007, fueling a concurrent increase in poaching.

Wasser’s method of using DNA to pinpoint poachers finally gives law enforcement a smoking gun to target elephant killers. “The only hope we have, given the urgency of the situation, is to stop ivory poaching at its source,” he says. “In the end, seizing ivory doesn’t really help. What helps is saving the elephants.”