BELFAST, Northern Ireland - For decades, Helen McKendry has demanded that Sinn Fein chief Gerry Adams come clean about the Irish Republican Army's abduction, slaying, and secret burial of her mother in 1972, and his alleged role as the outlawed group's Belfast leader who ordered the killing.

As detectives interrogated Adams for a second day over the unsolved slaying of the 37-year-old widowed mother of 10, who was falsely branded a British spy, the daughter who led a campaign for the truth says she's praying for a murder charge.

"I'm hoping against hope that he doesn't walk out free," McKendry said. "Everybody, the dogs in the street, knew he was the top IRA man in Belfast at that time."

McKendry, with her husband, Seamus, launched a protest campaign in 1995 against Adams' denial of IRA involvement in the slaying of Jean McConville. On Thursday, the 56-year-old said she found it hard to believe he was finally in custody.

Under British antiterror law, Adams, 65, must be charged or freed by Friday night, unless police seek a judicial extension to his interrogation.

Northern Ireland has met news of Adams' arrest for the 42-year-old crime with a mixture of resignation and cynicism. Supporters and detractors alike agree on one thing, though: Adams is too important a figure in the peace process to go to jail, and he's never going to talk honestly about his past command positions in the Provisional IRA.

Two decades ago, Adams initially insisted in brief face-to-face meetings with the McKendrys that the IRA was not involved. Finally in 1999, the IRA admitted responsibility for the slayings of nine long-vanished civilians and IRA members, including McConville, and offered to pinpoint her unmarked grave on a beach 60 miles south of Belfast in the Republic of Ireland.

That effort failed despite extensive digging. Then in 2003, a dog walker stumbled across her skeletal remains, with its bullet-shattered skull, protruding from a bluff above a different beach.

It was the bitterest of victories for the orphaned McConville children, whose lives were indelibly scarred by her disappearance. At the time, they ranged in age from 6 to 17; McKendry was 15. Since their father had died of cancer in 1971, authorities placed them in different foster homes and the children grew up strangers to each other.

McKendry says her mother's background as an outsider - she was raised a Protestant in east Belfast but moved to Catholic west Belfast after her marriage to the children's father, a Catholic - fueled irrational IRA suspicions. Northern Ireland's independent police complaints watchdog investigated the IRA's spying claims and cleared McConville's name in a 2006 report.