Mariyam Taburova and three of her roommates left the cramped apartment they shared here in Chechnya on August 22. She has not been seen or heard from since. The others, however, have been.Amanat Nagayeva and Satsita Dzhbirkhanova checked onto two flights leaving Domededovo International Airport two days later and, according to Russian officials, detonated explosives that brought down both airliners, killing 90. A week after those bombings, a woman believed to be Nageyeva’s sister, Roza, blew herself up outside a Moscow subway station, killing 10.The women — known to the neighbors as decent people making what they could of life in a place marred by destruction and destitution — are suspected of involvement in the deadliest wave of terror ever to rock Russia. And with Taburova’s whereabouts still unknown, the terror may not yet be over.They are not the first women linked to terrorism. At least two women, perhaps four, were among the attackers in the siege of Middle School No. 1 in Beslan. In Russia, such women are known as ‘‘shakhidki’’, the feminine Russian variant for the Arabic word meaning holy warriors or martyrs. The media knows them more luridly as ‘‘Black Widows’’ — women prepared to kill and to die to avenge the deaths of fathers, husbands, brothers and sons in Chechnya.But the circumstances that brought these women to suicidal attacks are not so simple. Their participation — despite Chechnya’s deeply patriarchal society, or perhaps because of it — reflects the radicalization of a war that began as a separatist struggle but has now turned increasingly brutal and nihilistic.It has also exposed the deep schisms that are tearing apart Chechnya, where few interviewed here this week spoke warmly of Russia or the Kremlin, but where all expressed horror at the bombings, the school siege, and other attacks that have been carried out for the sake of Chechnya’s independence.‘‘We were so shocked,’’ a woman who worked beside Dzhbirkhanova in Grozny’s central market said. Her eyes reddened with tears. ‘‘How could she?’’Chechens themselves have not embraced a cult of religious martyrdom, as have, for example, the Palestinians in the West Bank and Gaza, insurgents in Iraq, or extremist groups like Al Qaeda.In Grozny, where the four women lived and worked, there are neither posters nor graffiti celebrating their fate. Chechnya’s imams, leaders of a moderate Islam in an outwardly secular society, do not preach fiery sermons revering them. And those who knew the four women said they could not believe they were involved in any way. Rumors swirl. Some other fate has befallen them, their neighbours said, since they left two and a half weeks ago: kidnapping, arrest, death perhaps; anything but suicide.‘‘It is not normal,’’ said Khozh-Akhmed Israilov, a security guard in Grozny’s market who also knew Dzhbirkhanova, echoing others interviewed here. ‘‘How could someone do this to themselves? Only Allah can take life. She knew very well that to take her life was a sin.’’Unheard of when war ravaged Chechnya the first time, from 1994 to 1996, female suicide bombers have taken part in at least 15 attacks during the war that erupted again in 1999. Among those were the hostage siege of a Moscow theatre in October 2002, where 19 of 41 captors were women, and the bombing of a Moscow subway car in February, carried out by an unidentified woman.The women involved in the Moscow bombings were not, technically, black widows. Dzhbirhkanova, said to be in her early 40s, was divorced. So were the Nageyeva sisters, 26 and 24. All three divorced because they could not have children, something deeply stigmatized in Chechen life.A neighbour of the sisters who said she feared the kind of retribution that is all too common in Chechnya and would only speak on condition of anonymnity said she discounted that loss as a possible source for revenge.‘‘Amanat would not seek revenge after three years,’’ she said of the older Nagayeva sister, who in other accounts has been called Aminat, Amnat and Amanta. ‘‘Such things are never delayed.’’ Whatever their motivation, it was clear that all four women, like virtually everyone else here, led lives scarred by the violence of war and mired in the squalor and devastation of Grozny. Women armed for terror