So Freeze, after speaking to you for a bit we've agreed to deny this. First of all, you have no evidence of steamid, or any evidence of anything that Gregor may have done. Also, and more importantly, one doesn't need to call a KOS before shooting someone so long as they have a valid reason. In this case, from what you have said, his reason was valid as the detective shot you, therefore allowing him to assist, which isn't joining a gunfight as the detective is a proven innocent.

Thanks for the report and please continue to report anything you believe to be against the rules.