A Russian court has acquitted a top prison official charged in the death of whistleblowing lawyer Sergei Magnitsky in 2009.

The Tverskoy court Friday found Dmitry Kratov not guilty of negligence in causing Magnitsky's death.

Magnitsky, an anti-corruption lawyer died in prison after exposing an official corruption ring involved in the embezzlement of $250 million in tax money.

The case has become a rallying point for human rights advocates in Russia and abroad.

The U.S. Congress this month passed the Magnitsky Act, calling for sanctions against Russian officials accused of human rights violations.

Russia retaliated with a bill that bars Americans from adopting Russian children. Russian President Vladimir Putin signed the bill into law Friday.

The U.S. is the number one foreign destination for Russia's adopted children.