At the end of his trial in Vladikavkaz in southern Russia, Nurpashi Kulayev, a Chechen carpenter born in 1980, was found guilty on all charges, which included terrorism and murder. He had pleaded not guilty.
Prosecutors had requested the death penalty for Kulayev, but Tamerlan Aguzarov, the North Ossetian supreme court judge, said that a moratorium on capital punishment in Russia ruled that out.
"[Kulayev] deserves the death sentence but because the Russian government has introduced a moratorium on carrying out death sentences, I sentence him to life imprisonment," Aguzarov told the court on Friday.
Prosecutors told Russian news agencies that they would not appeal against the decision.
Kulayev was part of a group that took 1,300 hostages in a school in the southern Russian town of Beslan almost two years ago. After a three-day stand-off the siege collapsed into a bloodbath. More than half of the 331 people killed were children.
Aguzarov rejected Kulayev's claim that he had been forced to take part, and said witnesses' evidence contradicted his insistence that he had never threatened or harmed any hostages.