The chemist who unwittingly helped spawn the epidemic of synthetic drugs is hard to find. His phone numbers are listed under his wife's name. Strangers who call his laboratories at Clemson University are told he doesn't return messages.

To find him, you must travel deep into the Smoky Mountains. There, you will discover a stooped, elderly man padding about a house cloaked in mist.

John Huffman is his name. But he is better known by his initials: JWH. In the world of synthetic drugs, few letters carry greater notoriety. They have materialized on thousands of advertisements selling what are known as synthetic cannabinoids or marijuana. And government authorities have banned nine JWH substances, making him arguably the nation's most prolific inventor of outlawed synthetic marijuana.

Huffman's compounds, experts say, laid some of the earliest groundwork for what has become a scourge of cheaply made, mass-produced synthetic drugs. Since the 1990s, when Huffman cloistered himself in a lab and forged hundreds of compounds for medicinal purposes, the synthetic marijuana industry has become a multibillion-dollar juggernaut.

Despite the growing diversity of these synthetic cannabinoids, primarily produced by Chinese chemists intent on staying one step ahead of drug authorities, experts say many of them share a common ancestor in Huffman's work. Huffman's work "is how it all started," said Marilyn Huestis, senior investigator at the National Institute on Drug Abuse. "This is how it started. … John's very distraught that this has all happened."

Huffman never expected this late-life transformation into an international drug figure. His had once been an archetypal academic existence of research and teaching. Born in Evanston, Ill., he was always interested in chemistry and what it could mean for medicine. After getting his doctorate at Harvard University, he spent almost his entire career at Clemson in South Carolina, where he raised four kids, married three times and published any synthetic chemistry research he could.

In the late 1980s came the discovery of something called the cannabinoid receptor, which confirmed it interacted with the brain's sensory receptors. Its discovery marked a crucial moment in the development of synthetic cannabinoids. Rather than fumbling around in the dark, chemists could aim for a specific target — the cannabinoid receptor. Pioneering researchers started synthesizing fresh compounds to see how the receptor reacted to them.

But a strange thing can happen to scientists when navigating the frontiers of knowledge. It is easy to lose sight of outside applications. At the time, Huffman's second wife had multiple sclerosis. He was so preoccupied, he said, by the immediacy of his work and home struggles that he never realized he was unwittingly writing a recipe book of street drugs.

"The chemistry to make these things is very simple and very old," Huffman said. "You only have three starting materials and only two steps. In a few days, you could make 25 grams, which could be enough to make havoc."

The horror stories piled up. So the DEA in 2011 banned a list of synthetic cannabinoids. Three of the five were Huffman's.

The progression has worked like an evolutionary tree. The first and second generations of cannabinoids shared many characteristics with Huffman's. But as the tree widened, new compounds that emerged had less in common with their forebears. "This has been an evolution," said DEA supervisory chemist Jill Head, "and it had to start somewhere."