Once considered such a risk to reveal nuclear secrets that a grandstanding Russian politician wanted commandos to "liquidate" him, a former Russian atomic energy minister under indictment in Pittsburgh is a free man after serving two months of his 5¹/₂-year prison sentence.

A Moscow court released Yevgeny Adamov last week after suspending his sentence on a conviction of defrauding the Russian government of $31 million in a plot involving the sale of Russian uranium on the world market.

U.S. authorities will not comment on the release.

But Mr. Adamov remains charged here with money-laundering, conspiracy to transfer stolen securities and tax evasion in connection with another scheme to steal $9 million in U.S. funds intended to upgrade outdated nuclear reactors in Russia, Ukraine and Lithuania.

In 2005, a grand jury in Pittsburgh said Mr. Adamov, 67, and a partner, Mark Kaushansky, 56, of Monroeville, diverted the money into two shell companies with accounts in Pittsburgh, Delaware, France and Monaco.

Mr. Kaushansky, a Ukrainian immigrant and former Westinghouse nuclear power plant engineer who looked up to Mr. Adamov as a "father figure," is scheduled to be released in October from federal prison in Morgantown, W.Va., where he's serving 15 months for tax evasion.

But in Moscow, according to Russian news sources, Mr. Adam- ov continues to insist on his inno cence. He has vowed to appeal the verdict, seek acquittal and "investigate" those responsible for bringing the charges.

In February, a Moscow judge said Mr. Adamov and two Russian co-defendants conspired to essentially steal a majority of the shares in a U.S.-Russian joint venture, Global Nuclear Services and Supply, which was created to remove uranium from Russian nuclear weapons, downgrade it and use it in power plants in the United States.

Both of the accused co-conspirators were convicted but also given suspended sentences.

With Mr. Adamov no longer in custody, it's not clear what will happen to the U.S. charges, but he will probably never appear for trial here. The United States has no extradition treaty with Russia and the case likely will remain in limbo.

Mr. Adamov's lawyer for the U.S. case, Lanny Breuer, former White House counsel for President Bill Clinton, didn't return messages last week, but he has argued that Senior U.S. District Judge Maurice Cohill Jr. should dismiss the indictment.

The judge has already expressed doubts about the government's case, saying prosecutors can't prove that Mr. Adamov or Mr. Kaushansky skimmed international funds.

In determining a sentence for Mr. Kaushansky on tax evasion, he accepted the arguments of Mr. Kaushansky's lawyer, Fred Thieman, now Buhl Foundation president, that the men weren't hiding nuclear-safety money for themselves but trying to protect it from Russian banks.

Mr. Adamov said he funneled the money through Pennsylvania and Delaware companies he created so he could pay his scientists as head of NIKIET, the Research and Design Institute for Power under contract to improve power plant safety.

Had the money been paid directly to NIKIET scientists, many of whom were living below the poverty level, most of it would have disappeared into what Judge Cohill agreed was a "dysfunctional Russian banking system." No one trusted the banks, it seems.

Sergei Bocharov, who left NIKIET to become head of the International Atomic Energy Agency in Vienna, said he kept $25,000 in cash savings at his house instead of putting it in a Russian bank. When he wanted to transfer it to a Swiss bank, he gave it to NIKIET, which transferred it to Mr. Adamov's Delaware company, which in turn wired it to a Vienna bank.

Judge Cohill said the system that Mr. Adamov set up seemed to work. While other Russian scientific institutions were suffering, NIKIET thrived, even constructing a new building.

Judge Cohill said he doesn't believe the government's claim, built largely on evidence put together by Ed Reiser, considered among the best agents in the Criminal Investigation Division of the IRS, that the money transfers through various corporate entities and bank accounts was an "elaborate fraudulent scheme."

"The defendant's theory provides an alternative framework, one which we find plausible while we find the other unproved," the judge ruled. "We must give the defendant the benefit of the doubt."

The case, which Mr. Thieman, a former U.S. attorney, considers the most fascinating of his legal career, is ultimately rooted in the 1986 nuclear accident at Chernobyl and the upheaval following the collapse of the Soviet Union.

NIKIET had designed the RBMK reactor used at Chernobyl and at other plants throughout the former USSR.

Fearing another disaster, the United States and other nations in 1993 started the "Lisbon Initiative" to provide money and technical help to upgrade 15 power plants. Congress gave the effort $50 million a year.

Mr. Adamov, described as charismatic and brilliant, had been appointed head of NIKIET just after the Chernobyl accident and was hailed in Russia and abroad for cleaning up the site and redesigning the RBMK reactor to improve its safety.

He ran the agency until 1998, when President Boris Yeltsin appointed him to run the Federal Ministry of Atomic Energy.

But his career hit a rough patch in 2001 after the Russian Duma, which is equivalent to the U.S. House, issued a report that he had "openly demonstrated aspirations toward monopoly management of the government enterprise for his own personal gain."

The report caused a stir in Russia, but in his ruling in the Kaushansky case Judge Cohill said he doesn't believe it, noting that the Russian attorney general later found no evidence to support the allegations.

"We are not persuaded that the Duma Report is an accurate account of Adamov's activities," Judge Cohill wrote.

Still, Mr. Adamov left his post and eventually returned to running NIKIET.

After his indictment here in 2005, he became the focus of an eight-month extradition battle in Switzerland, where he had been arrested at the request of the United States.

American authorities wanted him to face trial in Pittsburgh, but Russian officials were afraid he'd reveal state secrets, including classified information about Russia's construction of a nuclear reactor in Iran, if he were extradited to America.

One legislator from a Russian political party known for outlandish statements even suggested that special forces kill Mr. Adamov rather than let him be extradited.

Some legislators feared he might give up sensitive information in exchange for leniency or under torture. Russia won the battle and Mr. Adamov has been there ever since.

But the trial and last week's early release has generated new suspicions in Russia that the prosecution there was little more than a show.

Environmental groups in Russia that have accused Mr. Adamov of corruption have said from the beginning that they didn't have much faith in the Russian court system.

"I don't think the investigation was carried out adequately and that Adamov will be subjected to adequate punishment," Vladimir Silvyak, co-chairman of Ecodefence environmental group, told the Web site for Bellona, a nonprofit that fights nuclear contamination in Russia."I am sure that they didn't turn him over to American authorities and instead trumped up a case in Russia in order that he not be subjected to more severe punishment."

Mr. Silvyak told Bellona that the spread of corruption under Mr. Adamov was "unbelievable" but that "nobody paid any attention to it so long as the Americans didn't bring him to account -- in Russia, it simply didn't interest anyone."

For his part, Mr. Adamov has always maintained that he's a champion of nuclear responsibility.

After the Chernobyl cleanup, he spoke at international conferences on the subject and in fact first met Mr. Kaushansky at a presentation he gave for Western scientists in 1988 in France.

When Westinghouse began courting NIKIET for business, Mr. Kaushansky became Mr. Adamov's translator, friend and business partner. The men and their wives grew so close that they became the shareholders in one of the U.S. corporations they established to manage investments, Omeka Ltd., of Monroeville. Omeka is one of the entities that the IRS here said was a shell company controlled by Mr. Adamov.

True or not, he's now free, the prosecutor in Russia says he won't appeal and the U.S. attorney's office can't do much about any of it, although $2.5 million in a Monaco account remains frozen.

Mr. Adamov apparently isn't going anywhere. According to news accounts, he's right back where he started -- running NIKIET.