All transactions are publicly visible, you can trace it in a bitcoin explorer, e.g. at blockchain.com but you cannot revert the transactions.
Successful scammers usually have to manage more and more addresses and most of them earlier or later do mistakes in staying private. So most of them could be caught. In practise (as of 2021) this doesn’t happen because most victims think it’s not possible or the loss value is too low or the police has far too few experts to follow it. But no scammer can feel save because you cannot improve the privacy after the fact. So each old case can be picked up somewhere in future.
This is how the tracing works:
With help of heuristics ( https://en.bitcoin.it/wiki/Privacy#Blockchain_attacks_on_privacy ) a cluster of bitcoin addresses is built which likely belong to the scammer. Then one investigates if at least one of the addresses in the cluster sent bitcoin to one of the millions of known exchange addresses. If this is not the case then you need to be patient. If there are links then the police can follow up directly (or via their colleagues in the exchanges country) to get all available information about their client who is likely the scammer. This information could be the id, the bank account number, a bitcoin withdrawal address or an altcoin withdrawal address. The first two options might lead to the real id of the scammer to claim the bitcoin back.The last two options provide the data to do follow on analytics actions.
Of course scammers try to avoid this by moving the coins dozens of times around, by using mixers or by exchanging the bitcoin into e.g. Monero forth and back. This can theoretically break analysis but in the most cases it doesn’t work over time. One little mistake and the house of cards breaks down. E.g. I saw scammers moving the coins more than 300 times and then they mixed it with old coins again. So the effort of moving 300 times was a waste of time. Or I saw people using Wasabi Coinjoin several times in a row and afterwards they mixed it again with coins from their earlier business. Then the Coinjoin isn’t helping to stay private.
Bottom line the problem of a scammer is that they should avoid spending their coins together but that its a pain to do this with an increasing number of addresses and many scammers aren’t aware how easy tracing is with the right analytical tools.
After investigating dozens of cases I know that in most cases there are traces to exchanges. I’m convinced that most scammers could be caught, but if this is successful the final success depends on the exchanges (not all support inquiries) and the cooperation of the involved jurisdictions of scammer, exchange and victim.
I wish you success in your case!