From the crack of dawn until late at night, stem cell researcher Hwang Woo-suk is at work in the lab, hoping to restore his credibility after a scandal that shocked the world.

Hwang gained worldwide fame in 2005 for his claimed breakthroughs in cloning human embryos and extracting stem cells from them.

In fact, he had done no such thing. It was, according to prosecutors, a "fraud unheard of in history."

An embarrassed South Korean government charged him as a criminal and stripped him of generous research funds and lavish perks, including personal bodyguards.

Now, Hwang — booted from the country's top-ranked Seoul National University — and about 30 loyal researchers have moved to a private lab outside the South Korean capital of Seoul to resume their work, details of which were revealed to The Associated Press.

"We knew that was not the professor Hwang we knew," Kim Sue, one of Hwang's chief researchers, said during a two-hour interview, the only one scientists connected to Hwang have given since the scandal. "That's why we told the professor that we wanted to work with him again."

Hwang himself turned down an interview request and referred AP to Kim instead. He is still defending himself against charges of misappropriating and embezzling private and government funds and is under investigation for allegedly buying human eggs — which is illegal in South Korea.

Whether Hwang can regain acceptance in the research community is far from clear. He embarrassed not only himself but also leading scientific journals that published his results.

Stem cell research, though controversial because it involves the destruction of human embryos, holds out significant promise for finding better treatment for a broad range of conditions, including Parkinson's disease, diabetes and spinal cord injury.

That's why Hwang garnered so much attention when he claimed to have extracted stem cells from cloned human embryos, something that no one has succeeded in doing.

It will be "very tough" for Hwang to rehabilitate himself, said Dr. Curt Civin, a stem cell researcher at Johns Hopkins University, though he did not rule it out.

"He faces a steep hill that he's going to have to climb," said Civin, also editor-in-chief of the journal Stem Cells, which had to retract a Hwang paper it published.

"I think he can climb it ... by solid, serious scientific discovery (with extensive documentation) every step of the way."

Whatever the odds, Hwang seems determined to make a comeback.

Work is in full swing at his new privately funded lab in Yongin, 30 miles south of Seoul. The team works days, nights and weekends, even living in a building near the lab funded by a private research foundation. The team declines to reveal cost figures.

"We also had to buy new equipment because we couldn't take any from the university lab — not even those professor Hwang bought with his own money," said Kim, her eyes welling with tears occasionally as she recalled the hardships Hwang and other researchers have experienced since the scandal.

Kim said the lab has already succeeded in extracting stem cells from cloned embryos of animals such as pigs and cows.

"If we had been working on human eggs, we could have produced human stem cells," she added. "We are confident that we can do it now."

It remains unclear whether the government, which must approve such work, will give Hwang another chance. Previously, Hwang had been the only scientist in Korea with a license to clone human embryos. Stung by the scandal, the government retracted it and has not issued one to anyone else.

"We are conducting research on animals so that when we are able to conduct research (on human embryos) we can immediately get down to it," Kim said. "Making stem cells from cloned human embryos is what we want to do the most and it's a great pity that we can't under the current situation."

Kim said Hwang will soon reapply for the license to resume research on human embryos, but didn't rule out the possibility that he may seek opportunities abroad.

"He doesn't have any plan to give up his research in South Korea and move overseas for the research any time soon," she added.

Still, Hwang headed abroad this month to meet with "scholars he is friends with for discussions on all possibilities," Kim said.

Kim, who has worked with Hwang for seven years, was a co-author of Hwang's discredited 2005 paper in which he claimed to have extracted stem cells from cloned human embryos that genetically match patients.

In fact, the stem cells had been extracted from ordinary embryos that grew out of fertilized eggs, an easier procedure that other scientists had already accomplished.

Hwang has insisted he did not aim to deceive the public, claiming a researcher at a partner hospital lied to him about extracting the stem cells from cloned embryos.

Government prosecutors have put Hwang on trial for allegedly accepting funds under false pretenses, embezzlement and illegally purchasing human eggs for research.

That has not stopped him from trying to get published again.

Besides cloning animal embryos, Hwang's lab also is trying to clone animals that can "produce materials useful to humans," Kim said.

Such materials could be used to create new drugs to replace more expensive ones currently in use, she said.

The researchers are also making genetically modified animals whose organs could one day be transplanted into humans, she said.

"There are many good research results that we want to boast about," Kim said, but declined to elaborate further. Papers are either being written or have been submitted to science journals for review, she said, and the lab hopes to have some published within a year.

Journal editors said Hwang's tattered reputation will cast a shadow on those attempts.

"Any submission from Dr. Hwang would take into consideration the irreparable harm that his previous misconduct has inflicted on the scientific enterprise," said Monica Bradford, executive editor of Science, which published now-discredited work by Hwang in 2004 and 2005, including the notorious paper in which he made his grandest claims.

Editors would have to balance the potential benefit to science of any claimed discoveries versus the possibility that they are bogus like the last time, Civin added.

"This would be a very quick reformation," he said, "and we'd have to worry about recidivism."