Delilah Williams last year pleaded guilty to murder, admitting that she participated in a pattern of abuse that led to the death of her 5-year-old stepdaughter.

But prosecutors said she provided an account of the circumstances of the death that included information authorities would not have known about. They urged U.S. District Judge David Ezra yesterday to approve a plea agreement that calls for her to serve a 20-year term rather than a life sentence for murder.

Assistant U.S. Attorney Marshall Silverberg said the stepmother's cooperation will allow prosecutors to present to a jury a "coherent case" against her husband, Naeem Williams, who faces the death penalty when he is scheduled to go on trial in May on a charge of murdering Talia Williams, his daughter.

Silverberg said Naeem Williams inflicted the fatal injury and Delilah Williams had stopped beating the child "some period of time" before the death.

Ezra approved the agreement.

But details of Delilah Williams' account, which was included in the plea agreement and has been described as providing "gruesome" details, won't be disclosed until she testifies at her husband's trial.

The trial would be the first involving the death penalty in the state in more than a half century since the Territory of Hawai'i abolished capital punishment in the 1950s.

Last week, the child's natural mother filed a Circuit Court lawsuit against the state alleging that child welfare officials didn't follow through on a complaint that Talia was being abused.

Naeem Williams, a Schofield Barracks soldier, and his wife were both charged with murdering the girl. The city Medical Examiner's Office said the death was from a head injury "due to battered child syndrome."

U.S. Attorney General Alberto Gonzales authorized the death penalty prosecution for the father, but not Delilah Williams.

ADMITTED ASSAULT

In pleading guilty in December, Delilah Williams admitted she assaulted her stepdaughter.

"The assaults, they were intentional and they weren't by accident or mistake," she said.

Silverberg told the judge that Delilah Williams is the only one of the three in the Williams household at the Wheeler Army Airfield apartment who can explain what happened because the child is dead and the father faces trial.

Silverberg also said Delilah Williams is giving up custody of her 2-year-old child.

Delilah Williams' lawyer, Judy Clarke of the federal public defender's office in San Diego, agreed with Silverberg and urged Ezra to approve the deal.

"She's making amends for her role in this offense," Clarke said about her client.

Ezra said Delilah Williams, under her account, is "not as culpable" as her husband and did not deliver the fatal blow.

"This has not been an easy decision for me, but I do believe it's the right decision," Ezra said.

The sentencing date will be set after her testimony during her husband's trial.

In the meantime, Delilah Williams' plea agreement, which contains her admissions, will remain under seal.

MAGISTRATE OVERRULED

In February, U.S. Magistrate Judge Leslie Kobayashi ruled that edited portions of the admissions must be unsealed when the judge approves the plea agreement. But Ezra last week overruled the magistrate at the request of Naeem Williams' lawyers, who fear the disclosure would violate their clients' rights to an unbiased jury and a fair trial.

Kobayashi had issued her ruling after a request by The Advertiser that Delilah Williams' account be made public.

Last week, Tarshia Williams, a South Carolina resident and the natural mother of Talia, filed a Circuit Court lawsuit against the state. It alleges that state authorities and others were notified about suspected child abuse, but failed to take action that would have prevented the death.

It said in July 2005, a relative of Talia's stepmother allegedly called the Child Welfare Services of the Department of Human Services to report that Talia was being abused.

Although the nature of the call and the information provided are in dispute, Child Welfare Services acknowledges it received a call about potential child abuse and was given the name Talia Williams, but claims the caller did not leave any contact information and it was not able to find a Talia Williams in its files, the suit said.

Department of Human Services spokesman Derick Dahilig said he and department director Lillian Koller have not seen the suit and declined comment.

The suit asks for an amount of money for damages that will be determined at trial.

Honolulu lawyer Mark Davis, who represents Tarshia Williams, said his client has been "devastated" and depressed over the death, but she's also "very angry."

"The mother feels this torture and death which resulted from his abuse was absolutely avoidable, given the advance notifications to multiple authorities about what was going on in this household," he said.

Reach Ken Kobayashi at kkobayashi@honoluluadvertiser.com.