It's well documented that a lot of this money goes out of the country by transferring it to a 'mule' with a bank account in the UK, who think they are doing something innocuous. They transfer it to the scammers either via cryptocurrency (basically untraceable) or previously, via an international money transfer service such as Western Union. The latter is also pretty much untraceable. You can pick up money anywhere in the world from these services with some ID. They don't need your address or to really check you are who you say you are, they just want to make sure you have the same name as the one the sender referenced.
Unless the destination country, the destination Western Union office and the person who picked up the money are all willing and able to co-operate, law enforcement in the source country is pretty much stuck.
But this is technically an invalid answer to the problem of file compression. An easy (!) way for data to be losslessly compressed would just be to have a registry of all files in existence, and to refer to each file by its index in the registry. (Like the prisoners who had told each other all their jokes so many times that now they could just quote them by number and everyone would laugh.) Data compression is supposed to be able to deal with novel but likely documents without needing to add them to a global registry.
Unless the destination country, the destination Western Union office and the person who picked up the money are all willing and able to co-operate, law enforcement in the source country is pretty much stuck.