Carl Force was processing suspiciously large amounts of money through a number of bitcoin and payment companies. Unsurprisingly, he kept triggering anti-money laundering / Know Your Customer checks--ironically, the exact kind of regulation that he himself was enforcing in his capacity as a DEA agent.
In the case of both Venmo and BitStamp, he tried to bypass any account blocks or KYC checks by waving around his status as a DEA agent. It's not clear how many companies he did this to. We only know of Venmo and BitStamp because they resisted.
In April 2014, BitStamp representatives messaged Force, asking him why he was accessing his account through Tor. He responded through the support ticket:
"I utilize TOR for privacy. Don't particularly want NSA looking over my shoulder :)"
BitStamp management found this message to be, well, incredibly weird. His account was blocked at this point (and unblocked and blocked again repeatedly for the rest of the month). At some point, BitStamp notified law enforcement, and the investigation into Force began.
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What went through his head when he typed that NSA bit? Did he really think that'll sway things in his favor