BAGHDAD – When police came hunting for a 19-year-old woman they believed had been recruited by al-Qaida to be a suicide bomber in a town north of Baghdad, they found she was already dead — slain by her father, who told police he strangled his daughter out of shame and then cut her throat.

The killing of Shahlaa al-Anbaky, reported by police Friday, appeared to be from an unusual melding of motives — part to defend the family honor, part to prevent her from joining the militants. But how much of each weighed in her father’s mind remains unclear, with police still investigating the details.

Al-Qaida has been recruiting women for suicide attacks because they can pass police checkpoints more easily than men by concealing explosives under an abaya, a loose, black cloak that conservative Muslim women wear. Suicide bombers have been al-Qaida’s most lethal weapon in Iraq, killing hundreds of civilians and members of Iraq’s security forces.

The slaying took place in the town of Mandali, about 60 miles northeast of Baghdad in Diyala province, which only a few years ago was one of Iraq’s deadliest regions, torn by attacks by al-Qaida and Sunni insurgents and vicious sectarian killings between Sunnis and Shiites.

After Sunni tribal militias turned on al-Qaida, the province has become much safer, like much of Iraq. But al-Qaida militants still carry out deadly attacks in the area.

Authorities were still trying to put together a complete picture of the killing.

A Diyala police spokesman, Maj. Ghalib al-Karkhi, said security forces had information the young woman had ties to al-Qaida and raided her father’s home Thursday. When questioned by police, the father, Najim al-Anbaky, told police he killed his daughter a month earlier because he found out she intended to blow herself up in a suicide attack for al-Qaida.

The father, described by authorities as a small-time trader of chickens and sheep, led police to her grave in the backyard. The woman had been strangled and then her throat cut for good measure, al-Karkhi said.

A senior Iraqi army official involved in the case gave a slightly different account, saying authorities looking for the daughter called the father in for questioning, not knowing Shahlaa was dead. It was then the father confessed to killing her, said the official, who spoke on condition of anonymity because he was not authorized to talk to the press. The different accounts could not immediately be explained.

Authorities dug up her body in hopes of learning more about how the killing happened. But the true reason behind the crime will likely remain a mystery.

The father was still in custody under investigation, though no charges had been filed so far.