What happens to confiscated guns?

Today is just pondering hypothetically out loud.
When a person in Illinois is convicted or pleas down an Aggravated Unlawful Use of a Weapon charge, which if you read my previous post you'd realize this is nothing more than a ridiculous felony for transporting your firearm incorrectly, the court seizes the firearm and makes the former owner sign a release allowing it to be destroyed, or used for "Police purposes."   There is no accountable information on the serial numbers of destroyed guns that I can find.   I had recently gone to my local sheriff's office and requested a Freedom of Information Act copy of the proof of destruction of these weapons.    There were no such documents available.   This means that destroyed firearms are not documented in any way.   As far as the records show, anything could be happening to these weapons, including being resold on the streets at a terribly low price to pad someone's pockets.