Clutching her daughter tightly to her chest, Zarah Ali leans close to the visitor and whispers her story.
She doesn't want the nearby camp guard to hear. If he learns that her 22-month-old daughter was fathered by a Boko Haram fighter, the gossip could sweep across the refugee camp, bringing her the stigma and ostracism that afflicts many women who were forced into "marriage" with the Islamist radicals.
Ms. Ali, the 20-year-old daughter of a Muslim farming family in northeastern Nigeria, knows more about Boko Haram than most. She was its captive – twice. She escaped once, fled across the border to Cameroon, and was captured again.
She spent months under Boko Haram's control. And despite the group's Islamist ideology and its claims of allegiance to the Islamic State movement, she scoffs at its professions of faith.
"Some of them pray, some of them don't pray," she says. "But all of them kill."
In her months of captivity, she remembers how Boko Haram would gather the people of the occupied villages and preach to them about how to "slaughter" their enemies. In contrast to their religious pretenses, they often recruited followers with offers of money and threats of violence, she says.
"They are unbelievers and thieves," she says. "They kill Christians, but they also kill many Muslims. They kill people and take their property."
New studies of Boko Haram are confirming what Ms. Ali has witnessed. The group was founded by a charismatic Islamic preacher, but religious beliefs are no longer the driving force behind the group. Many of its followers today are instead motivated by economic factors or anti-government grievances.
Mercy Corps, a U.S.-based humanitarian aid agency, recently interviewed 47 former Boko Haram members in northeastern Nigeria. Its study gives fresh insight into the brutal militia that has killed and abducted thousands of people in Nigeria and neighbouring countries.
The influence of religion in Boko Haram has declined since 2009 as the group became increasingly violent, the study found. "What emerged from stories of former members is that little religious or ideological indoctrination occurred, at least on a systematic level," the study said. "The youth we spoke to left disillusioned, whether because the violent tactics were too extreme or because their personal expectations were not met."
Boko Haram exploited the "deeply held grievances" of many communities in northeastern Nigeria, where people felt powerless and excluded from the political system, it said. "About half of former members said their communities at some time supported Boko Haram, believing it would help bring about a change in government."
In one of its most cynical recruitment tactics, Boko Haram offers business loans to youths who have little hope of formal jobs. Frustrated by Nigeria's economic inequality, they accept the loans in the hope of establishing themselves as traders. But in many cases Boko Haram soon demands repayment, using it as leverage for recruitment.
"If there is no money, the youth is forced to join Boko Haram or be killed," the Mercy Corps study said. "The tactics practised by Boko Haram resembled organized criminal gangs and their practice of doling out favours, only to demand repayment at a high cost."
The survey found that about half of the former members had been "coerced or pressured to join" – often because they needed protection or immunity from the group's attacks. "Young men described complicated business relationships in which they felt compelled to start attending Boko Haram preaching, or listen to audio cassette tapes, because of pressures put on them by buyers of their product, or their bosses."
Another study, by Nigerian scholar Abdul Raufu Mustapha, found that Boko Haram had its early roots in Islamic doctrinal disputes and radicalization in the 1970s, but that other factors have become increasingly important for its followers: poverty, unemployment, Nigeria's unequal economy, the collapse of local governments, and the chance for profits from robbery or kidnapping.
"The longer the violent insurgency has lasted, the further away it moves from its original doctrinal motivations, and the more its violence becomes routinized in everyday life," Prof. Mustapha wrote in a recent book, Sects and Social Disorder.
"For the youth directly involved either forcibly or by choice, violence becomes a way of life … more attractive to them than their previous marginalized, humdrum existence."
A report by the International Crisis Group this month said Boko Haram is becoming "strikingly similar" to the Lord's Resistance Army, the Ugandan-born militia that – like Boko Haram – began with a "radical religion-based rejection of society" and deteriorated into "a roaming gang, surviving by plundering goods and people."
As it expanded into border regions, Boko Haram absorbed local networks of illicit traffickers and bandits – networks that lacked any religious agenda but instead exploited Boko Haram's name and notoriety, the report said.
"Current attacks seem to be less about military strategy than extracting resources and sending a violent message that it is surviving," the Brussels-based think tank said.
"Increasingly they are on targets that offer easy plunder, including young captives, many of whom are turned into 'wives' and child soldiers … The easy access to brides, via coercion or otherwise, that Boko Haram gives to young militants … has probably been a major pull factor for the insurgency."
Ms. Ali was one of the many women forced into "marriage" after her village was invaded by Boko Haram. An insurgent warned her that he would kill her father if she refused his demand. "You have to marry him, or else they will kill me and force you to marry him anyway," her father told her.
The militant disdainfully tossed them 2,000 naira ($13) as a bride price. "I never liked him," Ms. Ali said.
She was pregnant within three months, but the insurgent was killed in fighting shortly afterward. She fled the village and eventually crossed the border to Cameroon – but then Boko Haram invaded again, capturing the region and taking her to a Nigerian town. Months later, she escaped captivity during a gunfight when Nigerian soldiers advanced into the town.
In Cameroon, her Christian relatives had considered her a Boko Haram follower because of her baby. They told her to convert to Christianity, but she refused.
Today she lives with her daughter, Kellu, at the huge Dalori refugee camp in Maiduguri, where thousands of people have taken shelter from Boko Haram. She says she has escaped stigma because the other refugees assume she is a war widow, like so many others. A mother without a husband is normal here.
She says she never thinks about the circumstances of Kellu's birth or the girl's father. "She is a blessing from God."