MOSCOW — The remains of the last tsar’s hemophiliac son and heir to the Russian throne, missing since the royal family was gunned down nine decades ago by Bolsheviks in a basement room, may have been found, an archaeologist said yesterday.

Bones were found in a burned area in the ground near Yekaterinburg, the city where Tsar Nicholas II and his wife and children were held prisoner and then shot in 1918.

A top local archaeologist said the bones belong to a boy and a young woman roughly the ages of the tsar’s son, Alexei, and a daughter whose remains have also never been found. If confirmed, the finding would solve a persistent mystery about the doomed family, which fell victim to the violent revolution that ushered in more than 70 years of communist rule.

It comes almost a decade after remains identified as those of Nicholas, his wife, and three of his daughters were reburied in a ceremony made possible by the Soviet collapse but shadowed by statements of doubt about their authenticity.

The spot where the remains were found this summer appears to correspond to a site described by Yakov Yurovsky, the leader of the family’s killers, said Sergei Pogorelov, deputy head of the archaeological research department at a regional center for the preservation of historical and cultural monuments in Yekaterinburg.

“An anthropologist has determined that the bones belong to two young individuals — a young male apparently aged roughly 10–13 and another, a young woman about 18–23,” he told NTV television.

Nicholas abdicated in 1917 as revolutionary fervor swept Russia, and he and his family were detained. The next year, they were sent to the Ural Mountains city of Yekaterinburg, where a firing squad executed them on July 17, 1918. Historians say communist guards lined up and shot Nicholas, his wife, Alexandra, their five children, and four attendants in a small basement room in a nobleman’s house in Yekaterinburg. The bodies were loaded in a truck and disposed of first in a mine shaft, according to most accounts. According to NTV, a 1934 report based on Yurovsky’s words indicated that the bodies of nine victims were then doused with sulfuric acid and buried along a road, while those of Alexei and a sister were burned and left in a pit nearby.