A Netherlands-based user of the now-defunct online black market Silk Road has plead guilty to a federal drug conspiracy charge.

Cornelis Jan Slomp admitted to importing controlled substances into the US and distributing 104kg of MDMA, 566,000 ecstasy pills and 4kg of cocaine, among other substances, globally from March 2012 to August 2013.

Slomp was arrested at the Miami International Airport in late August of last year, when he allegedly sought to meet with business partners who were looking to purchases his Silk Road operations and customers.

Gary Hartwig, special agent-in-charge of Homeland Security Investigations in Chicago, called Slomp a "prolific vendor on Silk Road" and went on to issue a stern warning to potential wrongdoers following in his footsteps.

Said Hartwig:

However, perhaps most interesting about the story is that the government has already sold more than $3m in the proceeds from Slomps' crimes, Assistant US Attorney Randall Samborn told CoinDesk, though he declined to offer any further specifics about the sale.

If convicted, Slomp faces up to 40 years in prison and a maximum fine of $5m.

Court documents suggest that Slomp, who used the vendor names 'UnderGroundSyndicate' and 'BTCMaster', conducted more than 10,000 transactions on the black market website, earning 385,000 BTC in the process.

The investigation against Slomp began as far back as April 2012, when US Customs and Border Protection officers in Chicago seized an envelope containing MDMA.

As a result of the ensuing investigation, during which 100 similar envelopes were discovered, Slomp was eventually determined to be the individual mailing the illegal substances.

US and Dutch law enforcement officials have been among the more active international groups at coordinating the arrest of bitcoin-based black market users.

Earlier this January, a 25-year-old US citizen was arrested after allegedly mailing a semi-automatic pistol to Dutch Law enforcement officials.

Slomp is among the first to plead guilty to charges in such cases. Most notably, alleged Silk Road mastermind Ross Ulbricht pleaded not guilty to charges against him this February.

More more on that ongoing case, read our most recent report here.

Package of narcotics via Shutterstock