There is a "high degree of probability" that bones found recently near the Russian city of Yekaterinburg are those of a daughter and son of the last czar, a forensics official said Friday.

If confirmed, the find would fill in a missing chapter in the story of the doomed Romanovs, who were killed after the violent 1917 Bolshevik Revolution ushered in more than 70 years of Communist rule.

The bones were found by archaeologists in a burned field near the Ural Mountains city where Czar Nicholas II, his wife, Alexandra, and their five children were held prisoner by the Bolsheviks and then shot in 1918. The discovery was announced in August.

"Investigators have made a preliminary conclusion that there is a high degree of probability that the bones ... belong to the Crown Prince Alexei and Princess Maria," said Vladimir Gromov, deputy forensic chief in the Sverdlovsk region, in televised remarks. "I want to emphasize, though, that this conclusion has a deeply preliminary character."

Thirteen-year-old Alexei was the heir to the Russian throne.

NTV television said in August that along with the remains archaeologists found shards of a ceramic container of sulfuric acid as well as nails, metal strips from a wooden box, and bullets of various caliber.

Prosecutors have announced they would reopen an investigation into the circumstances surrounding the deaths of the royal family, a decision that suggested the government was taking the discovery seriously.

In 1998, remains unearthed from a mining pit in Yekaterinburg and identified as those of Nicholas and Alexandra and three of their daughters were reburied in a cathedral in the imperial-era capital of St. Petersburg. The ceremony, however, was shadowed by doubts — including from the Russian Orthodox Church — about their authenticity.

Still, the royal family was canonized by the church in 2000.

Descendants of the royal family have repeatedly petitioned Russian authorities to declare Nicholas and his family victims of political repression.

On Wednesday, the Prosecutor General's office again denied that request, saying no court or "extra-judicial body" had issued any sort of execution or repression order for the royals.