The death of a District toddler Thursday was ruled a homicide yesterday, and police executed a search warrant at the home where she was living with her mother, another woman and at least two other children.

Twenty-three-month-old Briana Blackmond, who had been in foster care for nearly all of her brief life because of concerns that she was being neglected, died of blunt impact trauma to her head, Medical Examiner Jonathan L. Arden said.

Briana had been brought by ambulance to Children's Hospital on Wednesday. The little girl was breathing heavily but was unresponsive. Her mother told police the child had fallen down the stairs. But Arden said yesterday that Briana's injuries were not the result of such an accident.

Arden said that he could not discuss the specifics of the case, but that in general, "the severity of such a head injury is more consistent with a child falling out of a third-floor window or being in a high-speed motor-vehicle accident."

The toddler was returned to her mother 17 days ago after a judge granted a request by her mother's attorney to have the child returned in time for Christmas.

Assistant Police Chief William P. McManus said police yesterday searched the home on Bates Street NW where the girl lived and were conducting interviews in an effort to identify a suspect.

"The detectives are still looking for critical facts in the case to enable them to determine who will be charged," McManus said. He said both Briana's mother and another adult may have been in the home when the girl was injured.

Karen Kushner, a spokeswoman for the Child and Family Services Agency, which had been involved in the child's life nearly from the beginning, said neither she nor any of the agency's officials could discuss the case because it was confidential.

But interviews yesterday with child advocates and the little girl's attorney reveal a tragic chain of events that took a child away from a mother accused of neglect, placed her with a foster family and then returned her to her mother's home, where she died in a matter of weeks.

Briana was taken from her mother, Charrisse Blackmond, on June 9, 1998, four months after she was born, according to attorney Samuel Adewusi, who represented Briana as her legal guardian. Someone who suspected neglect called the child welfare system. When social workers arrived, they found Briana and five other children, up to age 11, "lethargic and filthy," Adewusi said.

All of the children were removed by social workers and placed in foster care. Briana was placed with a Northwest foster family that, Adewusi said, "really bonded with Briana."

But Briana's mother wanted her children back. And the eventual goal of the child welfare system is to reunite parents with their children whenever possible.

Adewusi said he and others argued in "four or five court proceedings" that Briana should stay in the foster home. He said that the issue was strictly one of neglect and that Blackmond has never been accused of abusing the children physically.

In December, the case came before D.C. Superior Court Judge Evelyn E.C. Queen. Adewusi said Blackmond's attorney, Jackie Walsh, asked Queen to send Briana and one of the other children home to their mother in time for Christmas. By that time, Blackmond had another child living with her--a baby born in April.

Neither Walsh nor Blackmond could be reached yesterday for comment.

Deputy Mayor Carolyn N. Graham, who oversees child welfare issues for Mayor Anthony A. Williams (D), said yesterday that she spoke to Ernestine F. Jones, the receiver for the city's child welfare system, who told her the agency wasn't comfortable returning the child to the family.

"The case was made that the child go home and spend the holidays with her parent," Graham said. "But the feeling of the agency was that there was still a tremendous amount of work that needed to be done."

However, Adewusi said a social worker for the Child and Family Services Agency told him that Blackmond had moved to a different home. Adewusi said the social worker was satisfied with the condition of the home and had no objection to Briana and a 3-year-old sibling returning home.

The social worker also could not be reached yesterday to comment. Adewusi said he visited the mother's home on Bates Street but still was not entirely satisfied.

He said he told Walsh that he would allow Briana to return home on the condition that the agency pay for a home helper to assist the mother with the children.

Adewusi said the attorney agreed, but that condition was never written in the attorney's motion to return the child.

"I feel a little responsible for the fact I didn't insist the homemaker be part of the motion that was filed by the mother's attorney," Adewusi said. "I should have insisted on having that in the record. . . . If I had objected, there would have been a hearing."