By ALISSA J. RUBIN, The New York Times, July 5, 2008

BAQUBA, Iraq — Wenza Ali Mutlaq walked a bit uncertainly up the long street near the main government offices here on June 22, the hot wind stirring her heavy black abaya. She passed the concrete barricades put up to ward off suicide car bombers and made her way alone, almost haphazardly.

Suddenly, a police car zoomed in. A policeman got out to talk with her. And then their lives were over — torn apart, along with 14 other people, by the huge blast of fire from her concealed explosive vest.

Ms. Mutlaq, who was in her 30s and whose attack was captured on a security video, was the 18th female suicide bomber of the war to strike in Diyala Province, which has been hit by female attackers much more frequently than any other province of Iraq, according to Iraqi police records and the American military. So far, 11 of the 20 suicide bombings carried out by women in Iraq this year have occurred in Diyala.

Why so many women? Why now? In a particularly painful twist, the phenomenon seems to have arisen at least in part because of successes in detaining and killing local members of Al Qaeda in Mesopotamia, a homegrown Sunni insurgent group that American intelligence officials say is led by foreigners.

The women who become suicide bombers often have lost close male relatives — a husband, a brother, a son — in fighting, because they became suicide bombers themselves or because they were detained by American or Iraqi security forces.

Ms. Mutlaq was no exception: her older brother had already taken the same path, detonating a suicide vest on June 10 during a shootout with Iraqi government forces.

“If there’s one single trend that I see, it’s the women’s relationship with the male figures that were members of A.Q.I. and were captured or killed,” said a senior military analyst, who spoke on condition of anonymity because he was discussing information that had not been released publicly.

The subordinate role of women in conservative, rural Sunni families in Diyala makes them particularly vulnerable to pressure, said Sajar Qaduri, a member of the Diyala Provincial Council and the only woman on its security committee.

“Although she is bombing herself and aiming to kill people, I feel these women are really victims of terrorism,” said Mrs. Qaduri, who is a Shiite and whose husband was kidnapped two years ago and has not been heard from since. “Only women in despair, in desperate situations, would do this. Dealing with such a phenomenon is not easy.”

She added: “Our Oriental society is not like your Western society. It seems in many of these cases the women have had their husband killed or sent to prison and she feels she has no choice, she is very depressed.”

Female suicide bombers are not a new phenomenon in Iraq or elsewhere, but they have been relatively rare. Since 2003, 43 women have carried out suicide bombings in Iraq, a tiny percentage of the total, according to the United States military. Though the first two cases came in the first year of the war, suicide attacks by women did not really become a trend until 2007, when there were eight such bombings in Iraq. All but one of the female bombers have been Iraqis and most are young, between the ages of 15 and 35, according to the police and American military analysts. Almost all the attacks have been attributed to Al Qaeda in Mesopotamia, which is also known as Al Qaeda in Iraq.

Diyala has been a stronghold for the group since it was chased from Anbar Province in the west in 2004. The province’s attraction was clear: it offers easy hiding places in its palm groves and orchards, and a Sunni-majority population that includes many people who supported Saddam Hussein and are sympathetic to the insurgency.

But in the past year, American and Iraqi forces have had much greater success in killing and detaining the group’s members in the province, as well as thwarting many of its bigger attack plots. The rise in female suicide bombings has directly coincided with the timing, and the locations, of Al Qaeda in Mesopotamia’s biggest loss of manpower in Diyala, Baghdad and Anbar.

“Al Qaeda is always innovating: finding new ways to work,” said Ghanem al-Khoreishi, the police chief of Diyala. “When we destroyed them in fighting, they started to use new methods. And because they knew that women are treated more gently than men, they began to use them.

“The people don’t search them so well even at checkpoints.”

Interviews with police officers and politicians, American military analysts and Iraqi women yield different views of the phenomenon. But many agree that the province’s traditional, conservative and still largely rural society is a factor.

In Diyala’s countryside, most women cannot imagine the world beyond the date palms they see on the horizon. It might be an hourlong walk to the next village, there are no telephones, and cellphones often do not work. Most of the women cannot read.

“Most of the women who have killed themselves are from the villages,” said Maj. Gen. Abdul Karim al-Rubaie, the head of the Iraqi Army operations center in Diyala. “She is living a very traditional life. She has no rights.”

“For that reason,” he added, “her ideas are very small.”

During Al Qaeda in Mesopotamia’s big push to take over Diyala villages, starting in late 2004, many families yielded to the extremists to protect themselves. Wide networks of villages that support Al Qaeda were created when subtribes, and sometimes even whole tribes, embraced the movement.

“In these families, they are terrorists: the conversations at dinner are about suicide bombs, about explosives, about improvised explosive devices,” said Col. Ali Ismari Fateh, a police commander who has been involved in hundreds of interrogations of people suspected of being insurgents.

Mrs. Qaduri, the provincial council member, said she believed that an element of sexual abuse may be involved as well. Many families marry their daughters off to local Qaeda leaders, known as emirs, at age 14 or 15. In some cases the girls are forced into marriage contracts in which they are married to a local emir, but if he dies or is captured, they are obligated to marry his successor and if he is captured or killed, that one’s successor.

At the same time, Diyala residents and officials say, militants from Al Qaeda in Mesopotamia have worked to instill their radical Islamist vision in the population. Almost immediately after moving in four years ago, they began holding religion classes for men and women.

“Even in Baquba, my niece went to some; she was shaken,” said Shamaa Abad al-Kader, the headmistress of a school for girls in Muqdadiya who also serves on Diyala’s provincial council.

“They gathered people in the villages; they brought women into Baquba and gave them lectures on how to behave,” Ms. Kader said. “These Al Qaeda men were going into the schools, into the mosques and they forced people to listen to them. My niece said the man who came to her school had a long beard and a sword with him.”

Insurgent recruiters and religion instructors add promises to the threats, too, assuring people that they will go to paradise if they die fighting for Islam — a sometimes alluring dream for many in their largely poor, uneducated audience, said police officials and politicians in Diyala.

In some cases, it may not just be a matter of co-opting or persuading vulnerable women. In one case in April recounted by Police Chief Khoreishi, a woman came to the station asking for protection; she was being forced to become a suicide bomber and trained to use an explosive belt by two members of Al Qaeda in Mesopotamia, one of them a close relative. The police now have her in protective custody, and two people suspected of being group members are in detention.

Iraqi police officials also say that a few of the bombings involved women wearing vests that were exploded by remote control, though it is unclear exactly how many because explosions usually destroy telltale design details about the detonators.

“There are two ways a suicide vest can work: there is a button they can push themselves and there is a remote control detonation,” Colonel Fateh said. “They follow her and if they think she is afraid to do it, then they will do it for her.”

Mrs. Qaduri believes that knowing the basic profile of the women who tend to become suicide bombers can inform policing: if a woman has a male family member who kills himself or is killed in the name of Al Qaeda in Mesopotamia or one of its sister organizations, it should be a warning sign that she or other close female relatives are at risk of becoming bombers.

Her dream is to start an intervention program that would take the women out of their homes and put them in shelters where they could not harm themselves or anyone else.

“We can predict that such a woman is ready to be used as a suicide bomber,” she said. “But at the same time, we don’t have any concrete proof that we can use to detain these women.”

Ms. Mutlaq’s life and death track the profile described by Mrs. Qaduri and others.

A native of the rural area south of Buhriz in southern Diyala, about 40 minutes northeast of Baghdad, she grew up in a landscape of date palms and orange orchards fed by irrigation canals.

Her tribe aligned itself early on with Al Qaeda in Mesopotamia, and her brother and husband became influential emirs, officials said. Buhriz was one of the most violent areas of Diyala in 2005 and 2006, with periods when there were nearly weekly bombings.

Last June, her husband was killed while fighting in Baquba, the province’s capital, around the time that the American offensive in the city began, according to Baquba police officials. Almost exactly a year after that, her brother detonated his suicide vest during fighting with government forces.

Twelve days later, she walked alone past the barricades.

An Iraqi employee of The New York Times contributed reporting from Diyala Province.