VOLGOGRAD, Russia — Russian security forces hunted on Tuesday for the husband of a bomber who blew herself up on a bus in southern Russia, killing six people and wounding more than 30. They also raised the possibility that Moscow, not Volgograd, was the bomber's original target.
Adding to the mystery surrounding Monday's explosion, Russian state television released pictures of the attacker's passport that looked different, even though they carried the same number.
Investigators say 30-year-old Naida Asiyalova, a native of the volatile province of Dagestan in Russia's North Caucasus region, was married to an ethnic Russian man who had joined Islamic militants. They say her husband, Dmitry Sokolov, has become a top rebel expert in explosives and could have been involved in equipping his wife for the suicide mission.
Sokolov has been on the run since he left his home in a Moscow suburb in the summer of 2012, according to the investigators.
The bombing in the southern Volgograd region was the first attack against a civilian target outside the volatile North Caucasus region in years, raising fears of a new wave of terror just three-and-half months before the start of the 2014 Winter Games in Sochi.
Soon after the attack, Russian state-controlled TV stations showed pictures of Asiyalova's passport which contained a black-and-white photograph of her wearing an Islamic headscarf in violation of Russian regulations. Some observers noted that photo would have led to her detention, if police had stopped her for an identity check. The shown passport looked entirely intact, which seemed unusual following the deadly suicide explosion.
On Tuesday, state television stations released a new picture of her passport that had a different color photograph without a headscarf and looked damaged. The passports shown Monday and Tuesday had identical numbers, and bloggers and online media quickly went abuzz with conspiracy theories.
The Investigative Committee, Russia's main investigative agency conducting the probe, said it hadn't released the first picture, only the second one shown Tuesday.
NTV, one of the three state-controlled nationwide TV stations, Monday's picture was a scan of Asiyalova's passport taken from her personal dossier at Russian security agencies that had been monitoring her for her suspected terror links. It said a photo of Asiyalova in a headscarf had been put atop the scan by a security agent.
Volgograd lies 650 kilometers (400 miles) northeast of the North Caucasus, where an Islamic insurgency has been simmering for more than a decade after two separatist wars in Chechnya. In Dagestan, the center of the insurgency, bombings and shootings occur almost daily. The Tsarnaev brothers, accused of carrying out the Boston Marathon bombings, have roots in Dagestan and Chechnya.
It was not clear why Asiyalova chose Volgograd, since she had a ticket for Moscow, authorities said.
Vladimir Markin, the spokesman for the Investigative Committee, said authorities are trying to determine whether Asiyalova had planned her attack in Volgograd or made an impromptu choice along the way. He said Asiyalova took a Moscow-bound bus from Dagestan, but left it in Volgograd and took a local bus, where she detonated her explosives Monday.
The bomb was rigged with shrapnel, which caused severe injuries and left many of the wounded in grave condition. Most of the passengers were students coming home after lessons.
Dmitry Yudin, a student who suffered a concussion and arm wound, said he had noticed Asiyalova when she boarded the bus because she wore a dark Islamic headscarf. He told The Associated Press the suspected attacker looked "calm and collected" and kept a low profile.
Rasul Temirbekov, a spokesman for the Investigative Committee's regional branch in Dagestan, said Asiyalova met Sokolov, a university student, in Moscow and recruited him to join the rebels in Dagestan. He studied Islam and the Arabic, took the nom de guerre of Abdul Jabbar and quickly gained a reputation with the militants.
Investigators believe Sokolov had prepared explosives for a suicide bomber who blew herself up outside the regional branch of Russia's Interior Ministry in Dagestan in May, killing 12 people.
Temirbekov said Asiyalova had a fatal bone illness, but her mother disputed that, telling the daily Izvestia newspaper that her daughter had stomach problems after taking diet pills but nothing serious.
Ravzat Asiyalova also said her daughter became strongly religious three years ago. She told Izvestia she disapproved of that and her daughter rarely called her, mainly to avoid arguments.
In an apparent retaliation for Monday's bombing, unidentified attackers set threw firebombs late Monday at a Muslim prayer house in Volgograd, police said. A custodian managed to put out the fire.
Vladimir Isachenkov reported from Moscow. Arsen Mollayev in Makhachkala contributed to the report.