Russian investigators confirmed on Wednesday that 90-year-old bone fragments found in the Ural region belong to last Russian tsar Nicolas II and his murdered children Alexei and Maria.

The Russian prosecutor's office said, "The final results of DNA studies, using three genetic testing systems, confirm the hypothesis that the second grave contained the remains of Grand Duchess Maria and Tsarevich Alexei."

The Bolsheviks seized power and shot and killed the Romanov imperial family July 17, 1918. Russian attitudes over the killing of the imperial family changed after the collapse of the Soviet Union in 1991.

The announcement came as Russian Orthodox believers are about to converge on Wednesday to commemorate the death of Nicholas II, his wife and his children by the Bolsheviks.

Archbishop Vikenty of Yekaterinburg will hold prayers and mass around the city of Yekaterinburg in the Ural mountains, where the last tsar and his family spent their final days.

The Orthodox Church has moved to canonize the Romanovs as saints and erected the Church of the Blood in their honor.