Two U.S. Democratic lawmakers have presented legislation to Congress asking that 60 top Russian officials be denied visas to the U.S. and have their assets frozen following the death of a prominent Moscow based lawyer, who had been hired to investigate corruption at the highest levels in the Russian government.

Hermitage Capital Investment, once Russia's largest investment fund with assets topping 4.5 billion dollars Russian, hired the Russian lawyer Sergei Magnitsky, 37, and six others to investigate Russian corruption and the loss of 230 million dollars.

"The cops were in on the scam," says William Browder, the founder of Hermitage Investment Fund. "They turned on every resource they had to come after the seven lawyers that we had hired and cooked up trumped up criminal cases against all seven of them."

Shortly after testifying against the Russian police and members of the country's tax authority and Interior Ministry, Magnitsky was arrested and placed in one of Russia's toughest prisons. The other six lawyers fled Russia for Europe.

"Sergei not only didn't go, but he was such a patriot that he went and testified against the police officers who stole the money," Browder, who has lobbied Congress to sanction members of Russia's interior ministry who allowed Magnitsky to be arrested and later die in prison. Magnitsky was arrested in November 2008, shortly after testifying against the police. The same police officers he testified against came to his house at eight o'clock in the morning as his wife was preparing their children for school and took him to prison.

The new legislation targets members of Russia's Interior Ministry. It is sponsored by Massachusetts Congressman Jim McGovern and Maryland Senator Ben Cardin.

"The authorities arrested the whistleblower, threw him into prison where he died," Senator Cardin told Fox News. "This is a horrible human rights violation and the authorities have done virtually nothing about it."

Magnitsky was held at Russia's notorious Butyrskaya prison, kept in a cell with eight inmates and four beds. The cell had no window panes so the icy winter air caused the prisoners to all become very ill. Open sewage drained into the cell and Magnitsky lost 40 pounds in a month.

"On November 16, 2009 he went into critical condition," Browder said. "Instead of treating him, they put him in a straight jacket, put him in an isolation cell and left him there for one hour and 18 minutes until he died."

Browder has the 450 complaints that Magnitsky filed from prison on a website that he started to expose Russian corruption called, russian-untouchables.com.

The Russian government says it is investigating Magnitsky's death and its Embassy would not respond to repeated requests for interviews on the subject.

The U.S. State Department has tried to raise the issue repeatedly with the Russian government. U.S. Undersecretary for Political Affairs William Burns told the Russian news agency, Interfax, "The Magnitsky case remains a matter of concern to the United States. We continue to believe that a full investigation is very important."

Jennifer Griffin currently serves as a national security correspondent for FOX News Channel . She joined FNC in October 1999 as a Jerusalem-based correspondent. You can follow her on Twitter at @JenGriffinFNC.