AUSTIN, TEXAS: The identity of the man who shot and killed an armed BLM protester on 25 July, has gone public. Sergeant Daniel Perry, an active-duty member of the U.S. Army stationed at Fort Hood, Texas, says that he shot 25-year-old Garrett Foster in self-defense after initially mistaking him for a law enforcement officer. 

Perry says Foster approached his vehicle with a rifle and motioned for him to lower his window. Which Perry did because he was under the impression Foster was law enforcement. However, according to Perry, after Foster raised his weapon and pointed it at him, Perry realized the rifleman was not law enforcement and shot him.

Source: https://thehill.com/homenews/state-watch/509987-fort-hood-sergeant-says-he-shot-and-killed-armed-black-lives-matter