How can I transfer a firearm after original owner has deceased?

I need a document signed by my mom to transfer my dad's firearm (deceased) to my husband (a retired police officer). At this time the firearm is being held at the precinct. I was told the form comes from the surrogate court, but so far I have been unable to speak to someone there who knows of this procedure. I am hoping to have the form emailed to me, so my mom can then sign and notarize it as required.