Tsar Nicholas II, his wife, their four daughters and son, and several servants, were shot dead by the Bolsheviks in a basement in the Urals city of Yekaterinburg in the early hours of July 17, 1918. The Romanovs were canonized in 2000.
The bodies of all the family, except for those of Prince Alexei and his elder sister Maria, were found in 1991 and buried in the St. Peter and Paul Cathedral in St. Petersburg in 1998.
The bones belonging to Alexei and Maria, according to DNA tests, were discovered near the city of Yekaterinburg in July 2007. The remains were examined by a total of 22 experts from 12 different laboratories.
The initial failure to locate the bodies of Maria and Alexei fueled rumors that they had somehow survived.
"When the second burial was found, it turned out that the overall weight of fragments was not enough for two people. And we suggested that another small burial site, a hole with the same amount of bones could exist on the territory," said Nikolai Nevolin, head of forensics for the Sverdlovsk Region.
The region spent around 6 million rubles ($240,000) to carry out DNA tests of the tsar's family members from the second burial site, Nevolin said. He added that tests would continue in case of a new discovery.
This year, the Russian Orthodox Church held services and processions across the country to commemorate the 90th anniversary of the killing of the last Russian tsar and his family.