Well the news says that they are not sharing any more further information regarding their on-chain deduction on how they figured it out. However, what we have as information is that he was paid in bitcoin, sent to a wallet, sent to some kyc-less exchange, bought monero there, moved to binance, and to bank accounts. So the question there is that how did he used monero, and still got tracked, he must be not hiding his wallet or anything, he must be doing nothing to save it, maybe using similar wallet address's multiple times. That seems like the only logical way that this would actually work, otherwise it wouldn't really make sense.