Jonathan K. Idema, a convicted con man who gained notoriety in post-invasion Afghanistan as a swaggering hunter of terrorists, then ignominy when he was imprisoned for taking Afghans hostage and torturing them, died Jan. 21 at his home in Bacalar, Mexico. He was 55.

Penny Alesi, a former girlfriend, said the cause was AIDS. A State Department spokesman confirmed the death.

Mr. Idema was a fast-talking, sunglasses-wearing, AK-47-toting fortune hunter and a flamboyant figure in Kabul, the capital, in the early 2000s. He flaunted his experience as a member of the Army’s Special Forces, or Green Berets. and let on that he was in cahoots with American and Afghan intelligence officials as he pursued the big rewards offered for leaders of Al Qaeda. He cultivated the news media, often with tall tales.

He provided broadcasters with videotape of supposed terrorist training camps; was interviewed as a covert operative by National Public Radio and Fox News; and insinuated himself into a book by the author Robin Moore, “The Hunt for Bin Laden.” Few knew he had served three years in federal prison in the 1990s on 58 counts of fraud. That information came out in 2004 when he was tried in Afghanistan for imprisoning and torturing eight men in a private jail that he and his civilian colleagues ran in the hope of getting information about terrorists and bounty money. (They wore uniforms with the American flag on the sleeves and called themselves Task Force Saber 7.) The case was widely compared to the abuse of prisoners at Abu Ghraib in Iraq.