I'm kinda winging it here so, as I recall from about 20 years ago, the following is what happened.
The Knoxville Police department had just started using Glock pistols. Maybe G17's but they definitely use G22's now. Anyway, an officer ended up shooting someone, who was already subdued and essentially prone, in the head. Killed her. It all started as a relatively minor incident to begin with.
This lead to that and that lead to the other. The question of Glock safety or lack thereof became a hot topic. There was a trial. I believe it may have been the first trial in which a gun manufacturer was sued. Gaston himself was subpoenaed and appeared in a Knoxville courtroom. I believe it was actually a civil suit brought by the victim's family.
That is how I loosely remember it. I believe the book will tell the whole tale much better.