Four years ago Dr. Abdul Qadeer Khan confessed to sharing nuclear secrets with some of the world's most notorious dictatorships.
Today he did a complete about-face.
"I was not involved in any nuclear proliferation," he told CBS News by telephone from his home in Islamabad.
Dr Kahn has been under house arrest for the four years since his televised confession in 2004.
On February 4, that year, he appeared on Pakistani national television after a government investigation into his role in transferring nuclear technology to Iran, Libya and North Korea.
"I was confronted with the evidence," Khan said, "and I have voluntarily admitted that much of it is true and accurate."
A metallurgical engineer, he had been awarded a gold medal by the Pakistani government after the country's successful nuclear tests in 1998.
However, he was disgraced after international evidence showed that he had stolen classified nuclear plans from the Dutch laboratory he had worked in, and shared them with other governments.
"It pains me to realize this in retrospect, that my entire lifetime achievement … could have been placed in serious jeopardy on account of my activities," he said in his TV confession, "which were based in good faith, but on errors of judgment related to unauthorized proliferation activities."
Today, though, Khan told CBS News that he had not written that confession, but merely read a document put in front of him "because of the promises that were made."
Back in 2004, Khan was never charged with any crime, and was given a full pardon by the Pakistani government a day after his television appearance.
Asked today whether he had had anything to do with the Libyan or Iranian nuclear programs, Khan said no.
"I have never put my foot on Iranian soil, I never met any Iranians.." he said. "And I never put my foot on the Libyan soil."
"When they asked my assistance, I told them, 'Go to the people in Dubai who supplied us.'"
Khan is now claiming that the parts necessary for a nuclear program are available for the asking from open suppliers in Dubai - a claim that, he feels, absolves him from any responsibility.
It's also a claim that is contradicted by solid evidence collected by the International Atomic Energy Agency, and the Pakistani, U.S. and Dutch governments.
In fact, the IAEA has been anxious to talk to Khan in order to understand better how nuclear technology proliferated during the early 1990s, and who was involved.
However, Khan - although he's made a decision to talk to the media - says he won't talk to the IAEA.
"I haven't violated any international laws. Why should I talk to them?"
Khan has re-emerged in public defiantly glib and with an apparently tenuous grip on reality.
According to the man known as the Father of the Islamic Bomb, we shouldn't worry that Iran has an active nuclear program, that there may be an arms race shaping up in the Arab world, or that India now has a large nuclear arsenal. Deterrence will keep us all safe.
"They have got very old civilizations. They are not fanatics as people try to project them," he said. "India knows it can be turned into charcoal - and Iran knows very well if they do any mischief … they could be turned into charcoal, too."
Asked by CBS News whether he had any regrets that his grandchildren would now grow up in a world facing a serious risk of nuclear weapons proliferation, Khan said, "Not at all."