Three employees of a now-defunct social-service agency have agreed to plead guilty and cooperate against their former colleagues in a federal case stemming from the starvation death of a 14-year-old child.

Christiana Nimpson yesterday admitted to two charges of fraud and one of obstructing justice. Today, Manuelita Buenaflor is scheduled to admit her part in the conspiracy, according to court documents.

They worked for MultiEthnic Behavioral Health, an agency that was paid at least $3.7 million by the city - in part to help watch over children at risk of abuse, like Danieal Kelly.

The girl, who suffered from cerebral palsy, died of starvation in a filthy, sweltering apartment in West Philadelphia in 2006 while she was under the supervision of the city Department of Human Services.

After her death, authorities charged that MultiEthnic workers failed to make the required visits - and then forged documents to try to cover it up.

Both Nimpson and Buenaflor have agreed to provide information to authorities to help what federal prosecutor Bea L. Witzleben says is a continuing investigation. She declined to provide details.

Nimpson might get three years and Buenaflor, because she was a supervisor, about four - although their cooperation could reduce those sentences, Witzleben said.

In a plea memorandum filed Friday, prosecutors said that Buenaflor was well aware that the agency's staff was creating phony records of home visits that never occurred - and that she created fake documents and backdated records herself.

After Danieal Kelly's death, prosecutors said, Buenaflor made sure that documents revealing the agency's failures of oversight were erased from MultiEthnic's computer.

Another agency employee, Sotheary Chan, is set to enter a guilty plea next week, Witzleben said.

None of the three was assigned to the Kelly family. But court papers lay out a wide-ranging conspiracy at the agency to cheat the government by failing to make the required visits to check on children at risk of abuse.

Nimpson, who worked for the agency for about four years, "frequently did not make the required visits to the families assigned to her," the plea agreement says.

The city DHS would provide MultiEthnic with advance notice of its audits - and even let the agency know which families' cases would be reviewed.

The agency even drew up fraudulent "alerts" that were supposed to let the city know immediately when the visits were not being made on time.

About half of Nimpson's documents were false, the plea says.

The three pleas are the first in the federal case, which has resulted in charges against nine of MultiEthnic's staff and supervisors.

In addition to the federal case, state prosecutors have also filed charges against nine people - including Danieal Kelly's parents.

Her mother, Andrea Kelly, pleaded guilty in April to third-degree murder and was sentenced to 20 to 40 years in prison. Her other children are still in DHS care.

Two of Andrea Kelly's friends have admitted to perjury. Charges against other DHS and MultiEthnic workers are still pending.

Julius Juma Murray, the MultiEthnic worker assigned Danieal's case, and agency head Mickal Kamuvaka face both federal and local charges. The grand jury convened by District Attorney Lynne M. Abraham indicted them on charges of involuntary manslaughter.

Contact staff writer Joseph Tanfani at 215-854-2684 or jtanfani@phillynews.com.