A first year law student could probably get most of the evidence suppressed claiming unlawful searches and seizures. Best just to find the rightful owner and return the items.
Exactly, with any halfway decent lawyer, none of these people could ever be convicted of ANYTHING.
You have houses being entered without warrants.
You have searches being done by non-law enforcement officers.
You have loot of untraceable origin.
You have homes that are forcibly abandoned.
You have extensive evidence of people entering and squatting in neighboring homes and buildings.
Any reasonable lawyers defense would read something like this, "Your honor, what really happened here is OBVIOUS. The original looter, whoever he was, must have discovered his own home flooded and took refuge in my clients home. When the looter faced starvation, he evacuated the city and left his loot behind".
Your job, as the prosecutor, is to prove that assertion FALSE. Good luck!
Of course, the looters we have on video will be MUCH easier to prosecute...if we can identify them. There's a big legal difference between having unidentified stolen goods show up on your abandoned property, and having video evidence of you actively stealing from closed businesses.