MOSCOW — DNA tests carried out by a U.S. laboratory prove that bone fragments exhumed last year belong to two children of Czar Nicholas II, putting to rest questions about what happened to Russia's last royal family.

Bone fragments dug up near the Ural Mountains city of Yekaterinburg are indeed those of Crown Prince Alexei and his sister, Maria, whose remains had been missing since the family was murdered in 1918 as Russia descended into civil war, said Eduard Rossel, governor of the Sverdlovsk region.

"We have now found the entire family," he said.

The confirmation could bring the tortured history of the Russian imperial family closer to closure and end royal supporters' persistent hopes that members of the czar's immediate family survived the massacre.

Nicholas II abdicated in 1917 as revolution swept Russia, and he and his family were detained. The czar; his wife, Alexandra, and their son and four daughters were fatally shot on July 17, 1918, in a basement room of the merchant's house where they were being held in Yekaterinburg

The remains of Nicholas, Alexandra and three of their daughters were unearthed in Yekaterinburg in 1991.