The bones, thought to be those of Prince Alexei and his elder sister Maria, were found in July 2007 near the Urals city of Yekaterinburg, where the tsar's family and several servants were shot by the Bolsheviks in 1918.
It was thought that only nine of the 11 bodies were covered in sulfuric acid, which was used to disfigure the bodies and hinder identification, as well as to prevent them from becoming the objects of veneration.
Although remains of the tsar and other family members were discovered near Yekaterinburg in 1991, the bodies of Alexei and Maria were not found, fueling a legend that some of the family survived the massacre.
"It has been established that the remains belong to a boy of about 12-14 years old and 150 cm tall and a young woman 159 cm tall," an expert with an identification center, Viktor Zvyagin, said. Alexei was 13 years old at the time of the killings, while Maria was 19.
They bodies found in 1991 were buried in the St. Peter and Paul Cathedral in St. Petersburg in 1998, although the DNA tests confirming that they were Romanov remains have since been challenged.
The Russian Orthodox Church, which has canonized the murdered Romanov family, called the 1998 burial "a political show."