One of the hackers behind online cyber-criminal forum Darkode has pleaded guilty to breaking into at least 77,000 computers, prosecutors said.
Eric Crocker, 39, of Binghamton, New York, was among 12 people charged in July when the international hacking forum was dismantled by US authorities working alongside law enforcement around the world.
Prosecutors say Crocker, who went by the online moniker 'Phastman,' used a hacking tool called Facebook Spreader to break into people's Facebook accounts and use them to spread spam messages among their contacts.
He and fellow Darkode hackers would then sell access to this 'botnet' of affected computers to people who wanted to send out large volumes of spam adverts and other commercial messages, for which they were periodically paid between $200 and $300 for every 10,000 active computer infections.
Crocker pleaded guilty to one count of violating the CAN-SPAM Act, a federal law on violations of Internet communication, and now faces up to three years in prison, a fine of $250,000, or both, the US Attorney's Office in Pittsburgh said in a statement.
The Federal Bureau of Investigation and the US Attorney's Office in Pittsburgh led the investigation into Darkode that has seen more than 70 people in 20 countries either searched, arrested or charged.
Sentencing will take place on November 23 2015.