Well, first of all, this all happened 5 years ago, so the trail long ago went cold.
I do this stuff for a living...
If I had a current IP address, then it could be tracked back to the ISP that owns that IP address, and possibly to a general geographic location like the city (maybe). However, if they came from a cell phone, then you can't even do that. Or, if they used any of the 50 different ways to fool the AAPK server into seeing a false IP address, then you will also get nothing.
AND, even if you are able to track the person's IP address back to an ISP, the ISP will provide zero information without a court order. Local law enforcement MIGHT have a cybercrimes department, but if not, they will refer you to the FBI cybercrimes task force. Either way, they will do NOTHING unless we are talking about very big money - hundred's of thousands of dollars. Anything less than that and it just isn't worth it to them.
Finally, even if you had a gung-ho & bored cybercrime investigator, all the evidence in the case needs to be treated like it is the lost ark of the covenant - it requires specialized computer forensics experts to be brought-in at step #1 and NO ONE else can touch the systems. It is incredibly easy for a smart defense attorney to show that the evidence from the servers could have been tampered with. All they need for reasonable doubt is to show that a hacker could set-up their client to be the fall guy and/or the gathering of the evidence contaminated the chain of custody. This is what always trips the techies up - we know how to look for data, so as soon as we find something odd, we start investigating, and the act of investigating is then used against us if we later try to bring in a forensics team. By the time the forensics team gets there, evidence that the techies have been poking around in the system is all over the place. When the DA sees that, they just throw up their hands and tell you sorry.
Bottom line: trust no one on the internet. No One.
"The Luggage had a straightforward way of dealing with things between it and its intended destination: it ignored them." -Terry Pratchett