Bloomberg did a nice job of pointing out that Murgio and Lebedev were long time friends of Gery Shalon, Ziv Orenstein, and Joshua Samuel Aaron and that the two separate criminal activities (the Pump&Dump money laundering scam and the Bitcoin money laundering scam) were very much related.
It appears that the hacking of JP Morgan was to gain access to names, addresses and e-mails that could be used for the stock promotional campaign done by the Stock Castle group
It sounds like these guys were all working for a much bigger criminal enterprise based in Russia.
Now we know why the Secret Service was so involved in this investigation. This article from last year when the hacking happened discusses the Secret Service's involvement and clashes they and the FBI had with JP Morgan about information sharing needed to conduct their investigation.
It sounds like they figured out right away that the hacking was done from a data center in St. Petersburg, Russia on the level of a data center that would used by low-level cybercriminals to send spam or operate botnets.