The security cameras do not have audio. The shot sounds may have come from over the police dispatch radio.
According to the police, Crawford ignored commands to drop the weapon.
After deliberating for three days, a grand jury decided not to indict the police officers on murder, reckless homicide, or negligent homicide. The grand jury also saw this video.
It seems strange that the local prosecutor couldn't get an indictment. There was no 'defense' argument made, and all he needed was half + 1 of the grand jury members to agree with him.
In the coverage of the event, there's no mention of race playing an issue. I don't doubt some will try to make it one.