In this Feb. 3, 2015 frame from video provided by the Fairfax County, Va., Sheriff, deputies work to restrain Natasha McKenna during a cell transfer, in Fairfax, Va. (AP/AP)

AMONG NATASHA McKENNA’S last words — or, perhaps, her last intelligible ones — were: “You promised me that you wouldn’t kill me. I didn’t do anything.”

That was all she had a chance to say before a six-man team of white-suited sheriff’s deputies, their faces obscured by helmets and visors, hauled Ms. McKenna, who was naked, from a cell at the Fairfax County jail. A short while later, after an 18-minute struggle to restrain her in which she was shot four times with a Taser, Ms. McKenna became unresponsive. She died five days later.

A video of the incident was released Thursday by Sheriff Stacey A. Kincaid. It is a chilling thing to watch.

What’s striking is not that the deputies used excessive violence with Ms. McKenna — they pinned her down and kneeled on her but didn’t seem intent on hurting her. The incident is brutal — six men manhandling an average-size woman — but it does not show punching or chokeholds.

The real problem is that it was the wrong approach to take with a woman, diagnosed since childhood with schizophrenia, who was mentally ill. Ms. McKenna is approached and treated as if she were a creature from an alien galaxy, not a human being.

In the video, which lasts more than 45 minutes, no trained mental health professional is present to assist with her extraction from her cell. No deputy tries to speak with her. No tactic beyond force is contemplated.

While Ms. McKenna was reportedly a difficult inmate — in earlier incidents at the jail, officials said, she scratched, fought, bit and threw urine at deputies — in the video she does not appear possessed of “super-human” or “demonic” strength, which deputies later attributed to her.

In the end, unable to secure her legs in a specially designed chair, one of the deputies shot her with a Taser — twice in the leg, twice in the arm. Minutes later, Ms. McKenna seemed to lose consciousness, although deputies seemed not to respond to that reality for about 12 minutes.

Ms. Kincaid, the sheriff, released the video after prosecutor Raymond F. Morrogh decided not to bring charges against the deputies. In releasing it, she said it was her “responsibility to ensure something like this never happens again.”

To that end, Ms. Kincaid said she has ordered a review of policies and procedures — something she has been promising for months. Let’s hope that review includes procedures covering Tasers, the use of which Ms. Kincaid suspended at the jail a few months ago.

The sheriff also pledged that henceforth deputies will receive crisis intervention training designed specifically to deal with mentally ill inmates, something she once dismissed as unnecessary for personnel working inside a jail.

That counts as progress, although it has been halting and unnecessarily slow. So does Ms. Kincaid’s announcement that her office will embark on what she called a thorough review of the incident leading to Ms. McKenna’s death.

Ms. Kincaid’s most important initiative — if it results in real reform — is her plan to divert mentally ill defendants into appropriate mental health treatment facilities. That would be the most effective way to prevent horrific incidents such as Ms. McKenna’s death.