ANAYAH WILLIAMS was two months old when Frederick County child protective services removed her from her parents’ custody in 2012 after she suffered a fractured skull and rib. Police investigated and concluded the injuries had been inflicted but were unable to determine who was responsible. No charges were brought, but the little girl remained in foster care until about a month ago, when she was returned to her parents.

The judgment had been made that it was safe to reunify the family.

Late last Friday, an unresponsive Anayah, now 21 months old, was taken from her parents’ home and later pronounced dead at Frederick Memorial Hospital. Police said there were visible marks and bruises on her body. Results of an autopsy are pending. Both parents have been arrested on child abuse charges: Frankie A. Williams, the father, for inflicting the fatal injuries; Stephanie E. Williams, the mother, for failure to protect and provide treatment. The Frederick News-Post, citing court documents, reported that the father told police he “made a mistake and hit his daughter.” The girl, according to the newspaper, was in pain for six hours before 911 was called.

Something went horribly wrong here, and it’s important to determine if it was because of human error or a breakdown in the system.

Frederick County State’s Attorney J. Charles Smith III explained to us the difficulty of prosecuting the 2012 incident. Doctors consulted by authorities said the parents’ explanation that the baby had fallen out of her bassinet couldn’t account for the injuries. But given the parents’ denials of wrongdoing, the absence of other witnesses and — as is often true in cases of child abuse — a victim who couldn’t speak for herself, no case could be built. The parents petitioned the court for return of their daughter and began a gradual process of increasingly longer visits before they were eventually awarded full custody. At one point, sources told us, Anayah returned from one such visit with bruises. The couple’s other daughter now is 5 months old, and authorities are investigating whether she has been abused. The 2012 incident is being reinvestigated.

Our calls to the Frederick Department of Social Services were referred to Maryland’s Department of Human Resources, whose spokesman, Brian M. Schleter, left a voice message promising to call back with information but had not as of Thursday evening. Angelita Plemmer Williams, a spokeswoman for the Maryland state court system, to which we were referred by the Frederick Circuit Court, said she could provide no information on a case involving a minor, including the name of the judge.

The confidentiality that cloaks the child protection system may have been understandable when Anayah was alive and her privacy needed to be shielded. Now the only thing being protected is the system that failed to protect this little girl.