A FEW months before Ms. Adonizio left Belize, Mr. McAfee introduced himself as Stuffmonger on Bluelight. He had started a thread on the site about MDPV, one of several drugs known by the deceptively benign name of bath salts. He wrote that he wanted recreate what he called “super perv powder,” a light brown version of MDPV that he tried in 2006. The drug delivered a jolt to his nether parts that he never forgot. “I think it’s the finest drug ever conceived,” he wrote in his first Bluelight post, “not just for the indescribable hypersexuality but also for the smooth euphoria and mild comedown.”

The point of his Bluelight posts, Stuffmonger wrote, was to describe his experiments to recreate “the tan,” as he christened the drug, a slightly darker version of MDPV which he said was no longer commercially available. He hoped that others would chip in and help. To that end, his posts offer chemistry-set pointers (“If the yellow-green color happens, don’t worry, you haven’t lost anything. Add water, pour it back in the flask and heat slowly”) and warnings (“A 100 mg dose of the tan will merely guarantee fatigue and sore genitals from nonstop sex and keep you up for 24 hours max”).

The posts were accompanied by photographs of Stuffmonger’s lab, and close-up shots of powders he had created. Among other Bluelight posters, there were some skeptics, including a person who figured that Stuffmonger was shilling for a company selling MDPV. But there were true believers, too, including a guy who said he’d followed Stuffmonger’s instructions and wound up with a drug that he and his girlfriend had tried with a success that was almost frightening. The two had sex with such riotous abandon, he reported, that the next day they could hardly look at each other.

In all, Stuffmonger posted more than 200 times, and his “last activity,” according to Bluelight’s profile page, was two days before the discovery of Mr. Faull’s body.

Whether these Bluelight posts were just a charade, as Mr. McAfee contends, is impossible to say. But Dr. Paul Earley, an addiction specialist in Atlanta, said that MDPV users commonly rhapsodize about their early experiences, claiming the drug makes them alert, activated and in some cases fantastically randy.

“That’s part of the danger,” Dr. Earley said. “The absence of any apparent side effects lures users into heavier and heavier doses and at some point, for reasons we don’t fully understand, MDPV becomes extremely toxic. Users become psychotic and paranoid. They hallucinate monsters. Often they think the police are after them. That is the classic MDPV profile.”

Mr. McAfee has written on his blog that he has not taken drugs or had a drink since 1983. He told Joshua Davis, a reporter for Wired who has written an e-book about Mr. McAfee, that pre-1983 he had been an alcoholic and a heavy cocaine user — snorting lines in his office at a Santa Clara, Calif., company called Omex and downing a bottle of Scotch a day. He said he was coping with the scars of a terrifying childhood in Roanoke, Va., where he grew up with a father who was an alcoholic who beat him and his mother; the father later committed suicide.