Here’s yet another reminder that Bitcoin, while private, is not truly anonymous. The feds can still locate and arrest folks who use the cryptocurrency for alleged criminal activity. 

A federal criminal complaint unsealed Monday charges Charlie Shrem, former CEO of the former bitcoin exchange BitInstant, with conspiracy to commit money laundering and operating an “unlicensed money transmitting business.” The complaint alleges that Shrem and an “underground bitcoin exchanger” named Robert Faiella (aka “BTCKing”) sold more than $1 million in bitcoin to users of the former Silk Road, a den of online iniquity in which users could reportedly buy and sell drugs, weapons and assassination attempts.

Or, as the press release from the U.S. attorney for the southern district of New York put it, Shrem and Faiella “schemed to sell over $1 million in Bitcoins to criminals bent on trafficking narcotics on the dark web drug site, Silk Road.” Shrem, currently a vice chairman at the Bitcoin Foundation, was arrested at JFK airport on Monday. The feds shut down Silk Road last October.

The director of an exchange typically has no idea why people are buying and selling bitcoin, but the complaint alleges that Shrem personally bought drugs on Silk Road and that he knew from communications with Faiella that his alleged co-conspirator was operating a bitcoin exchange service for Silk Road users.

BitInstant previously made headlines after the Winklevoss twins invested $1.5 million in the exchange, and again as the subject of a class action suit for allegedly misrepresenting the speed of its service. BitInstant ceased operation last July, according to the complaint. Redditors discussed its apparent disappearance last August in this thread.

Read the full criminal complaint below: