ATLANTA -- A woman accused of helping her husband kill their daughter because they believed she was demonic has pleaded guilty to murder.

Valerie Carey, 29, has been sentenced to life in prison for the child's death at a downtown Atlanta motel last year. She's agreed to testify against her husband as part of a plea bargain. Investigators said Christopher Carey stabbed the child with a knife until it broke.

Police found 8-year-old Quimani Carey on the floor of a extended stay motel room after finding the couple walking naked down a busy street in freezing temperatures. They were carrying their two other children.

Quimani’s arms had been broken, she had been strangled and she had been stabbed several times, prosecutors said. Authorities said pages from the Bible had been torn out and thrown on the girl's body. Testimony indicated that the girl's father believed she was demonic and had been implanted with a chip that sent signals to the planet Jupiter, which would allow the family to be tracked.

The woman pleaded guilty to several charges, including malice murder, felony murder, aggravated assault and first- and second-degree cruelty to children. During the court proceeding, testimony indicated that the man and woman both suffered from dual psychosis, a condition in which they both believed and saw each other's delusions.

Valerie Carey will be eligible for parole after serving a set number of years in the death of her daughter. Quimani was killed Jan. 19, 2004.

Prosecutors said they were told by relatives that the mother had suffered from a history of mental illness.

"We thought the rapture would take the four of us to heaven," a tearful Valerie Carey said to the judge during sentencing. "But I ended up in jail and a mental hospital. Everything I thought was real in my life proves to be false."

Prosecutors had recommended life in prison with the possibility of parole for the mother and life in prison with no parole for the father.

Christopher Carey, 31, remains jailed without bond and faces a death penalty trial if he does not agree to a plea deal.

It was not clear how long Valerie Carey would have to serve before she is eligible for parole. The judge ordered that she continue to receive mental counseling while incarcerated.