The mother of Russian lawyer Sergei Magnitsky says the administration of a Moscow detention center created "torture conditions" that killed her son while he was in custody.
Natalia Magnitskaya testified on October 2 at the trial of the sole defendant in the case -- Dmitry Kratov, former deputy warden at Moscow's Butyrka detention center.
Kratov is charged with negligence leading to Magnitsky's death in November 2009.
Magnitskaya said that more individuals must be held accountable for her son's death.
The judge rejected Magnitskaya's request to launch additional investigations into the case.
Authorities say Magnitsky -- the attorney for the London-based Hermitage Capital Management -- died of heart failure while awaiting trial on charges of tax evasion.
Magnitsky's supporters say he died after being beaten and tortured in custody.
Magnitsky's case led to the replacement of the leadership of Russia's Federal Corrections Service.
Based on reporting by Interfax and RIA Novosti