Guilty pleas were registered for two men in federal court in Newark, N.J. on Thursday for several computer fraud charges, reported by Reuters.
Their hacking and spamming campaigns were believed to have earned them $2 million in profits.
Tomasz Chmielarz (33) and Devin McArthur (27) pleaded accountable to various fraud charges. The two were detained in December, alongside Timothy Livingston, for their supposed positions in a number of hacking and spamming operations.
The charges state that Livingston, who owns a spam company, employed Chmielarz to create software that sends out spam that conceals its sender and bypasses junk mail filter systems.
Chmielarz, prosecutors said, confessed that together with Livingston he hacked into email accounts and obtained control of company mail servers.
The three are also speculated to have collaborated in stealing the private details of up to 60 million Americans.
Livingston has pleaded not guilty. His court date is October 13, 2016.
The case is U.S. v. Livingston et al, U.S. District Court, District of New Jersey, No. 15-cr-00626.