FAIRFAX, Va. — The death of an inmate in a northern Virginia jail has been ruled a homicide, and detectives believe the cause was an injury sustained before the woman was arrested.

Fairfax County police said Friday that autopsy results show 53-year-old Henrietta Smith, of Washington, D.C., died in September of blunt force trauma to the head.

A news release says officers first came into contact with Smith in August while responding to an assault call. A preliminary investigation revealed an acquaintance hit her in the head with a blunt object before officers arrived.

Police say Smith was offered medical treatment at the scene, which she refused. Medical staff at the Fairfax County Adult Detention Center evaluated her before she was admitted.

Detectives are still working to arrest the person or people responsible.