A 7-year-old Bedford-Stuyvesant girl was killed in her apartment yesterday amid an Administration for Children’s Services investigation into a report that the girl had been abused.

The medical examiner’s office ruled the Nixmary Brown’s death a homicide, Ellen Borakove, the spokeswoman for the office, said. The girl died as the result of child abuse syndrome – meaning she sustained injuries all over her body for some time – including blunt impact injury to the head with brain hemorrhage, she said. One police official said the girl’s body was covered in bruises.

Police yesterday were questioning the girl’s mother, Nixzaliz Santiago, 27, and stepfather, Mr. Rodriguez, officials said. As of press time, they had not been arrested or charged with any crime.

At about 4:30 a.m. yesterday, while her five other children and common-law husband, Ceasar Rodriguez, 27, were home in their Greene Avenue apartment, Ms. Santiago found Nixmary, her eldest daughter, lying face up on the floor in the rear bedroom. Ms. Santiago ran upstairs to notify a neighbor, and the neighbor followed her back down and called 911. Emergency Medical Service technicians declared Nixmary dead at the scene.

The other five children were taken to Woodhull Medical and Mental Center in Bushwick for an evaluation before children’s services staff took them in for questioning. It did not appear that they had been abused, sources said.

Despite the allegations, there were no domestic violence reports filed against Mr. Rodriguez, who was the biological father of two of the children. Ms. Santiago was the biological mother of all six children.

According to news reports, it appeared that Nixmary had been bound and held captive prior to her death.

Mayor Bloomberg responded to the death: “A 7-year-old is dead. ACS was called. Somebody alerted them. They tried to do an investigation, obviously not fast enough.”

Abuse allegations regarding Nixmary had been filed in the past, and children’s services was in the process of investigating one such complaint.

A spokesman for the Department of Education, Keith Kalb, said officials at P.S. 256 Benjamin Banneker, where Nixmary was in second grade, notified children’s services two times regarding possible abuse. Sources close to the investigation said school officials were concerned because Nixmary had an excessive number of absences in May and suffered a black eye in December. Children’s services found the May report of abuse to be unfounded and was investigating the December claim.

Police officials said the May report was actually for child malnourishment and the December complaint was regarding a laceration to Nixmary’s face.

The commissioner for children’s services, John Mattingly, issued a statement in response to Nixmary’s death: “While members of Children’s Services staff were in the middle of investigating a report of abuse involving her family, which we received on December 1, the fact of the matter is that this little girl is no longer with us.”

Children’s services came under fire recently after two children died after they were reunited with their biological parents.