Someone Cashed My $750 Check!

So I’ve been waiting on this check to come in for about a year now- for some background it’s from my tribe as I’m a member of a Federally recognized tribe. The $750 was a part of a series of four checks issued from Covid.

There was a lot of back and fourth with me calling the tribe to make sure they sent it to my NEW address and not my old one, they said it was sent back to their office because they sent it to my old address originally. So in December the tribe said they had it in their hands and they’ll send it to my new address.

Fast forward to today. I called saying it’s been months since someone said they would forward it to me. The admin said all four checks were cashed including the last one. I’m floored so I go through my mobile check deposit to see if I’m just dumb and cashed it. Nope I didn’t. So I asked her when it was cashed- she said December 19th to a checking account that’s not mine!

My theory is that my scummy neighbor at my last address (who was fond of opening my packages as well) cashed my check.

What are my next steps here? I just want my money :(