Re: For fun..
I don't think the article stated they were conducting business using bitcoin. They may have used Monero which is very much more anonymous. And even if they were using bitcoin, it is quite common for these types to use "tumbling" services which make it hard to trace the final wallet address.
These stories are also interesting in that it seems L.E. are still unable to penetrate the markets themselves and have to rely on analogue detective work.
And yes, I would like to know how the $8.8 million figure was arrived at.