Evidence of WHAT?!?
This isn't the perp's gun; and it can be PROVED that the perp was at the scene and in possession of the shotgun; and was attempting armed robbery totally in absence of this "piece of evidence"; it makes as much sense as confiscating the brown stained pants the cashier was wearing, to prove he crapped them in order to show 'he feared for his life' during the robbery.
Are all COPS' guns confiscated (let's think SWAT teams here) and put into the evidence locker every time they are pulled, let alone fired; and kept until any resulting case is adjudicated?
Is the gun being kept as evidence in case that Nazir is ever prosecuted for shooting the perp...a "case" that has never been filed?
How much IRRELEVANT "evidence" do cops need, for the DA to prove that these perps were at the scene; were armed; and demanded money?
Let's just close down the business, and put the whole damned thing into the evidence locker, while they're at it.
You don’t like it, change the rules of evidence.