Re: How
They can only be tracked to the point they're converted into Monero. From there they could emerge anywhere as Bitcoin again, or Ethereum or cash...etc.
You can only track the address to which they were sent. When they are exchanged for another crypto you need to know which crypto they were converted to and the address the new crypto was sent to. This is impossible once you get into Monero.
The exchange will know your initial Monero wallet, but beyond that once it's all split up it's a crap shoot.