In my opinion, it depends if you are CIRG or normal duty FBI. If you are CIRG you should respond to panics hostage situations shootings etc. If you are normal patrol FBI you should investigate suspicious things and respond to calls such as shootouts and panics
In my opinion that kill can be certified as crossfire he walked into the fire, nothing you can do about it but I advise you to ask an admin for confirmation just in case. ✌🏻