Russia has charged two doctors in the 2009 death of imprisoned lawyer Sergei Magnitsky after he spent almost a year in a pre-trial detention center.

A spokesman for the Investigative Committee said Friday it had established a direct link between Magnitsky's death and the actions of the doctors in the prison.

The chief physician at Moscow's Butyrskaya prison, Larisa Litvinova, was charged with manslaughter by negligence, while the prison's deputy chief, Dmitry Kratov, was charged with negligence. They are the first people charged in the case.

The 37-year-old Magnitsky, who worked in Russia for a British-based investment fund , accused Russian police officials of stealing fund documents as part of a scheme to pocket hundreds of millions of dollars. Those same police officials arrested Magnitsky in 2009 on what his supporters say were phony tax evasion charges.

He spent nearly one year in jail in poor health, denied the care that his supporters say could have saved his life. He died in an isolation cell in November 2009 of untreated heart problems and pancreatitis, despite filing dozens of complaints demanding medical treatment

Magnitsky's supporters say the investigation did not go after the real guilty parties. The Interfax news agency quotes the head of the presidential council for human rights, Mikhail Fedotov, as saying the charges brought against the doctors are a step in the right direction but that everyone responsible for Magnitsky's death in prison should be punished.

In late July, the U.S. State Department imposed a travel ban on dozens of Russian officials suspected of involvement in Magnitsky's death. U.S. law requires the State Department to deny visas to anyone accused of human rights violations, including torture.

Russia's Foreign Ministry responded harshly to the visa restrictions, saying it would not leave such unfriendly steps unanswered. The ministry promised to take adequate measures to protect the rights of Russian citizens against what it called “unjustified moves” by foreign states.