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. Last Updated: 07/27/2016

Crash Probe Turns to Bombs, 2 Women

Traces of the powerful explosive hexogen have been found in the debris of the two passenger jets that fell from the sky minutes apart last week, all but confirming fears that they were the targets of an organized terrorist attack, the Federal Security Service said.

Investigators also said that two Chechen women bought tickets at the last minute for the flights at Moscow's Domodedovo Airport on Tuesday and that their bodies were the only ones unclaimed by relatives so far -- raising suspicion that they may have been suicide bombers.

In its first official acknowledgment of terrorism, the Federal Security Service, or FSB, announced Friday that it had found traces of the explosive in the wreckage of the Sibir Tu-154 that crashed in the Rostov region.

"A preliminary analysis showed that it was hexogen," FSB spokesman Sergei Ignatchenko said, Interfax reported.

Ignatchenko also said the FSB has identified "a circle of people that may have been involved in the terrorist act on board the Tu-154 plane."

His statement came hours after a group called the Islambouli Brigades claimed responsibility for both crashes.

On Saturday, the FSB announced that it had found traces of hexogen on

the debris of the Volga-Aviaexpress Tu-134, which crashed in the Tula region.

The Tu-154 was bound for Sochi, while the Tu-134 was headed for Volgograd. They crashed three minutes apart Tuesday night.

The death toll from both crashes rose to 90 on Friday after rescuers found the scattered remains of a 44th person on the Tu-134. The remains are believed to be of Amanta Nagayeva, one of the two Chechen women who took the flights, Kommersant reported. Izvestia gave her first name as Aminat.

Chechen police on Friday opened an investigation into Nagayeva and the other Chechen woman, identified only as S. Dzhebirkhanova, whose remains were also scattered.

Many of the other bodies at the crash sites were found relatively intact -- suggesting the two women were in close proximity to the bombs, Kommersant and Izvestia reported.

Both women bought their tickets shortly before the planes took off, investigators said.

Nagayeva's brother disappeared three years ago when unidentified armed men took him away from the family's home in the Chechen village of Kirov-Yurt, said the village's head, Dogman Akhmadova, Izvestia reported.

Federal troops are often blamed for such disappearances in Chechnya, and rebels have in the past recruited the female relatives of killed and missing people to act as suicide bombers.

Nagayeva was 27 and worked as a market vendor in Grozny, Chechen police told Kommersant.

Dzhebirkhanova is only known to be from Chechnya's Shali district, Izvestia reported.

Details about the explosions -- which tore off both planes' tails -- emerged over the weekend. Only one body from the Tu-134 was burned, indicating that the explosion may have been triggered in a small space, such as the toilet at the rear of the plane, Kommersant said.

Dzhebirkhanova was assigned to seat 19F, the fifth row from the back, Sibir said in a statement. She didn't have carry-on or check-in luggage, Sibir deputy director Mikhail Koshman said.

The group that claimed responsibility for the crashes, Islambouli Brigades, said five "holy warriors" were on board each plane but did not describe how they downed the planes. It published a statement Friday on an Arabic-language web site known to be a mouthpiece for Islamic militants, and the authenticity of the claim could not be independently confirmed.

The group said the attacks aimed to help the rebels in Chechnya and threatened more attacks. "Our mujahedin, with God's grace, succeeded in directing the first blow, which will be followed by a series of other operations in a wave to extend support and victory to our Muslim brothers in Chechnya and other Muslim areas that suffer from Russian faithlessness," the statement said, according to The Associated Press.

The claim did not mention al-Qaida, but a group with a similar name -- the Islambouli Brigades of al-Qaida -- claimed responsibility for an attempt to assassinate Pakistan's prime minister-designate in July.

Moscow says al-Qaida supports rebels in Chechnya.

The Islambouli Brigades did not say whether rebels carried out the plane attacks, but a rebel spokesman has denied any involvement.

The group said the crashes did not go exactly as planned. The attackers "were crowned with success though they faced problems at the beginning," it said, without elaborating.

The attackers may have initially wanted to board different planes. Dzhebirkhanova first bought a ticket for a larger Sibir plane, an Il-86 that seated about 350 passengers and was scheduled to take off for Sochi at 9:20 a.m. on Wednesday, Koshman said. She then changed the ticket for the Tuesday night flight to Sochi, he said.

Vladimir Lutsenko, former head of the KGB's counterterrorism department, said that if the Chechen women were the attackers, they may have changed their plans after becoming scared or facing problems getting the explosives and detonators past airport security.

The attackers may have had an accomplice at the airport who bypassed security and handed them explosives and detonators, Izvestia reported, citing an unidentified bomb expert with the police.

Another problem could have been a failure to send suicide bombers to more planes, said Peter Sederberg, a professor at the University of South Carolina who specializes in international terrorism. "Maybe they wanted more planes, three or four, and they got two," he said by telephone.

The masterminds behind the crashes also may have wanted to send the planes into prominent targets, rather than explode them in midair, but the plan failed for some reason, Sederberg said. "That is an important speculation -- that it was supposed to be something imitating Sept. 11," he said.

If the bomb on the Sibir Tu-154 had been connected to a timer and the flight had left Moscow on time, the plane would have blown up at about the time it was over Sochi, where President Vladimir Putin was vacationing at the time.

The FSB refused to comment on the claim by the Islambouli Brigades. "We don't comment on such statements, especially when their authenticity hasn't been established," a spokesman said, Interfax reported.

Sederberg said the claim may be an attempt to misdirect the authorities, but added that it is not uncommon for previously unknown groups to claim responsibility for terrorist acts. The group is "more likely an offshoot of a more known phenomenon," he said.

The Sibir Tu-154 sent two signals to air traffic controllers just minutes before exploding -- an SOS call and a hijack alert, Interfax reported, citing an unidentified aviation official. Earlier reports differed on whether the plane had sent an SOS or hijack signal.

Putin has ordered the FSB to study how other countries combat hijackings, "including proposals to use the Israeli system of checking and monitoring air security, which today is recognized as the most effective in the world," FSB spokesman Ignatchenko said Saturday.

Transportation Minister Igor Levitin, who is overseeing the investigation into the crashes, visited Domodedovo Airport on Sunday and said the country must develop unified standards for airport security.

Finance Minister Alexei Kudrin said the government will set aside 2 billion rubles ($68.5 million) for a new counterterrorism program next year. The program will include efforts to increase security measures in public places, including the Moscow metro, he said Thursday.

NATO, meanwhile, condemned the downing of the planes as an apparent terrorist attack Friday, saying NATO and Russia will be "relentless" in responding to the "scourge" of terrorism. Counterterrorism is one of the main areas where NATO is trying to work more closely with Russia under a 2002 cooperation agreement.