A retired correction officer who shot a man to death in a Brooklyn subway station in March will not face charges.

The Brooklyn District Attorney says there was not enough evidence to charge 69-year-old William Grooms in the killing of Gilbert Drogheo.

It happened after a fight at the Borough Hall station.

Cell phone video shows a physical altercation between Grooms and Drogheo and in the last shot someone can be heard saying "Don't Make Me Shoot You."

Police said Drogheo and another man attacked Grooms on a subway train before the fight spilled into the station.

Grooms was licensed to have a gun.

Brooklyn DA Ken Thompson says his office reviewed the video and questioned witnesses before deciding not to bring charges.

In a statement, Thompson said, "While the death of this young man was indeed tragic, we cannot prove any charge of homicide beyond a reasonable doubt."