I've kept this article handy as a nice primer on bitcoins and hawalas, and how they are used/abused:
http://priceonomics.com/hawala-the-w...-mans-bitcoin/
Data experts are likely having a field day with bitcoin though as every transaction gets logged to the blockchain, meaning that every transaction is permanently traceable.
There are bitcoin laundering services that are out there now in an attempt to obfuscate that, but I imagine that once someone in an intel group ties a bitcoin ID to a user, backtracing transactions isn't terribly difficult.