I wish the victims luck in this. As a retired detective, this is a complex case involving victims in several states along with the feds (interstate commerce) and the postal service being involved. I can tell you that, at least where I live, the postal investigators try to dump almost every small case they get on local pd when it comes to mail theft or mail fraud. They bigger cases they try to dump on the County Attorney or Attorney General's Office. I'm not trying to say they are lazy...they run on skeleton crews here in AZ and they're overwhelmed. The problem is - so are the local PD. The feds...forget it. They have absolutely no interest in cases like this...again, due to staffing. When I say a case like this - likely small amounts of money (under 10 grand), and only a property/fraud crime. The BATFE will sometimes get involved if numerous guns are illegally transferred, but that's rare. I once had an agent tell me if it doesn't involve illegal sears, machine guns, suppressors or multiple straw purchases by one individual or group, they aren't interested. I was taken aback by that, but that was one comment from one agent over 10 years ago.
Recently, we had a home-based FFL broken into and IIRC 21 guns were stolen (nothing class 3). The ATF got involved by basically holding our coats while our detective unit and SWAT did the warrant hit, but we took the case entirely. All charges were state charges. Incidentally, the county attorney declined to charge the driver of the suspect vehicle - who took the guns from the main suspect as he walked out of the garage and placed them in the rear of the SUV they were driving.
Another thing to consider is...even though the crime was committed in Ponca City, OK, the accused in a crime has the right to face their accuser. If this goes to trial, the victims will have to drive/fly to OK if it's a state trial.
I can also tell you that almost no company will tell the police anything regarding electronic communication/data storage without a search warrant. These are very labor intensive types of cases. I wish this wasn't the case...I can't tell you what a PITA it is when dealing with banks/companies who are *victim* of a crime and they won't tell you crap about the fake accounts/communication/data the suspects used without a warrant (I closed cases in that event due to an uncooperative victim).
This case alone will likely require numerous search warrants/subpoenas (each web site used, his cell phones (and then any apps he was using on his phones require their own warrant), his cell phone providers, his internet provider during each transaction, his computers, his house. You can combine a few of those on 1 warrant (his house/phones/cars), but you have to be very careful with how you word your affidavit. Frankly, I am very surprised Ponca City PD has run with this. I used to race motocross and the nationals were there at the time. It is not a big town, but hey...good on them!
The best solution is for them to offer him a sweetheart plea deal that stipulates full victim reimbursement.
It's interesting he's converting the USPS money orders into bitcoin and sending it away. I wonder if he's been duped by some "female" overseas who he thinks is here in the US to do this? It's a stretch, but possible. I had a couple cases along those lines and proving he "knew" or "should have known" what he was doing was hard to prove if he clams up. The IP addresses of the communication/postings would be critical in that case because it would need to be shown that he made the claims that he possessed the items for sale and solicited payment, rather than someone else doing so and then directing payment to him in Ponca City and converting the money to bitcoin.
Sorry for the rambling response.
