WASHINGTON — The death of a Fairfax County jail inmate has been ruled a homicide, but police think an injury she suffered before her arrest is what killed her.

Autopsy results just received by Fairfax County Police show 53-year-old Henrietta Smith of D.C. died last September from blunt force trauma to the head.

Smith was arrested for a parole violation and drug possession Aug. 20, after police responded to a reported assault in the Alexandria area of the county.

A preliminary investigation found Smith had been hit on the head before officers arrived.

Smith refused treatment at the scene, and got a medical evaluation before being admitted to the Adult Detention Center.

On Aug. 31, Smith suffered a medical emergency in her cell, police said.

She was taken to a hospital where she died a week later.

The jail is operated by the Fairfax County Sheriff’s Office, and the county police department is the agency in charge of investigating sheriff’s office’s in-custody deaths.

Police say they’re still following leads in an effort to make an arrest in the case.