See if you can contact the author of
Breaking Mixing Services, he may know a thing or two about this.
It's a Bitcoin mixer. They have coinjoin and advanced feature of mixing bitcoin. The audit job is to try to track back the mixed funds.
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Their advanced feature is to mix your bitcoin with XMR and then from XMR to bitcoin.
Who's holding the XMR in this case? If it's the mixer, it's still a black box to the user: Bitcoin in > Bitcoin out. In that case I see no point in using XMR. If it's the user, there are 2 separate actions: Bitcoin in > Monero out and Monero in > Bitcoin out. In that case the connection between Bitcoins in and Bitcoins out should be pretty hard to find. Theymos wrote this:
In order to get decent privacy, you have to do something like this:
1. Convert BTC to XMR (using your own Monero wallet, not a hosted wallet).
2. In two or more transactions of random amounts, move XMR from that wallet to a different wallet/account.
3. Optionally, you can repeat the above step with additional wallets/accounts for greater anonymity.
4. Preferably in two or more transactions of random amounts, convert the XMR in your last wallet in the chain to BTC.
Ideally, all of the above should be performed over as long a period of time as you can tolerate.