The mother of a 10-month-old girl who was killed at a Garfield day care center in June said yesterday she's upset that no charges have been filed in her daughter's death and feels aspects of the police investigation remain undone.

"Everybody always says how sorry they are and how their hearts go out to us, but I just want them to work harder and investigate this so much harder," said Rhonda Moore, whose infant daughter, Marcia Poston, died when a 7-year-old girl pulled her from her baby chair at Bray's Family Day Care and threw her to the carpeted concrete floor at least twice, police say. "I want to know what happened."

The Dearborn Street day care center has since shut its doors, and the 7-year-old girl, the granddaughter of the center's operator Loretta Bray, is slated to face a dependency hearing in juvenile court next month. Authorities say the case is closed.

"Based on the evidence we have right now, we're not going to file any charges," said Mike Manko, a spokesman for the district attorney's office. "If in the future any additional evidence is brought forward, we would certainly review it."

Ms. Moore said she still has questions about what happened inside the day care June 6, when 20-year-old caregiver Ashley Swann was supervising five children, police say, but had gone upstairs to change a child's diaper, leaving the other four children unattended. She returned downstairs when she heard a commotion and found Marcia on a loveseat with blood around her ears. Then, police say, she called 911.

The infant was pronounced dead shortly before 1 p.m. at Children's Hospital.

Among other concerns, Ms. Moore said she questions police accounts of how long Ms. Swann was upstairs and away from the other children.

"I just can't wrap my head around it," she said. "There's just so many questions that I have. ... There's just too many holes."

Ms. Moore said she has hired an attorney and believes an adult should be held accountable for her daughter's death.

Pittsburgh police Lt. Dan Herrmann said yesterday that detectives have forwarded their findings to the district attorney's office and are finished investigating the death. He said detectives "covered all the bases," researching Ms. Swann's background and that of the day care center. He said they gave Ms. Swann a polygraph test, but wouldn't disclose its results.

"It is a tragic accident, and there is someone responsible," Lt. Herrmann said. "Unfortunately, she is 7 years old."