In 1991, the bodies of Tsar Nicholas II, Tsarina Alexandra, and three of their daughters were exhumed from a mass grave near Yekaterinburg. They were identified on the basis of both skeletal analysis and DNA testing. For example, mitochondrial DNA was used to match maternal relations, and mitochondrial DNA from the female bones matched that of Prince Philip, Duke of Edinburgh, whose maternal grandmother Princess Victoria of Hesse and by Rhine was a sister of Alexandra. The bodies of Tsarevich Alexei and the remaining daughter were discovered in 2007. Repeated and independent DNA tests confirmed that the remains were the seven members of the Romanov family, and proved that none of the Tsar's four daughters survived the shooting of the Romanov family.