He did so without registering his operation as a money- transmitting business.

He pleaded guilty in September to one count of conspiring to operate an unlicensed money transmitting business.

Faiella, who was known online as BTCKing, pleaded guilty in September to operating an unlicensed money transmitting business.

Maxim Chukharev, 28, pleaded guilty in Manhattan federal court to conspiring to operate an unlicensed money transmitting business.

Former manager Azzedine El Amine pleaded guilty last month to charges of conspiracy and operating an unlicensed money transmitting business.

Faiella pleaded guilty to one count of operating an unlicensed money transmitting business, which carries a maximum sentence of five years.

But there's another operation that runs both a marketplace where Bitcoins are bought and sold and a fully compliant money- transmitting business.

Marmilev's plea came almost a year after Liberty co-founder Vladimir Kats pleaded guilty to money laundering and operating an unlicensed money transmitting business.

He is to plead in New York federal court to one count of aiding and abetting the operation of an unlicensed money- transmitting business.

But prosecutors later dropped the criminal claim, replacing it with a civil complaint charging Gold and Silver with operating as an unlicensed money- transmitting business.

Murgio had argued that bitcoin did not qualify as "funds" under the federal law prohibiting the operation of unlicensed money transmitting businesses.

Lebedev was arrested in July along with a Florida man, Anthony Murgio, for engaging in a conspiracy to operate an unlicensed money transmitting business.