“Did they actually arrest the person and were they charged?”
Not to even mention that an “arrest” is NOT a “conviction”. You are guilty of nothing until you are convicted. But they keep property such as firearms even if you are never convicted and deemed guilty.
To keep should require (A) a conviction and (B) proof from the state that such items were either used by the owner in or the fruit of the crime the person was convicted of.
If the person is not arrested and charged you may not touch their stuff.
Unless both A and B have been met you need to give their stuff back.
Just recently the Supreme Court in my state ruled that you could not just take someone's car because they gave someone, who was a drug user, a ride when there were no drugs found on the driver, on the passenger or in the car.
You would think that would be logical.
But no. She had to take to the highest court in the state to get her 2006 Ion back.
This taking of people's stuff is out of hand.