Washington ? The deadly takeover of a Moscow theater last year by Chechen rebels is being investigated by U.S. authorities who are trying to determine whether criminal charges can be brought against attack organizers.

A federal grand jury and the FBI are looking into the October 2002 attack, said two U.S. government officials who spoke on condition of anonymity Wednesday. Russian officials have provided U.S. investigators with several leads in the case, they said.

The siege ended when the Russian government sprayed a powerful gas into the theater. More than 120 of the 800 hostages were killed, including Sandy A. Booker, 49, who was visiting Moscow from Oklahoma City. It is not certain whether any of the attackers survived.

Booker’s fiancee, Svetlana N. Gubareva, survived the attack, which killed her 13-year-old daughter.

In a telephone interview with The Associated Press on Wednesday, Gubareva said she testified voluntarily last week before the federal grand jury in Washington about the attack, and also spoke to FBI and Justice Department officials.

Gubareva is part of a Russian association of relatives and survivors of the theater attack in trying to demonstrate that the deaths should not be blamed solely on the Chechen rebels but also on the Russian government, because of Moscow’s use of the deadly gas.

“Chechnya is part of the Russian state, and the state is responsible,” Gubareva said. “I equally blame both.”

Gubareva is pursuing a $5 million lawsuit against the Russian government.