A Canadian citizen has pleaded guilty to aiding Russian intelligence officers in a 2014 hack of Yahoo that exposed as many as 500 million accounts. The defendant, 22-year-old Karim Baratov, is the only arrest to come out of the Yahoo hack as the three other individuals facing charges live in Russia, which obviously has no interest in extraditing them to the United States.

Prosecutors have stated that two of those charged are officers in Russia’s spy agency, the FSB, while the other is known Russian hacker Alexsey Belan. They believe that FSB officers Dmitry Dokuchaev and Igor Sushchin directed the hack and contracted Baratov when their targets used email accounts outside of Yahoo’s system. The summary issued by the Northern District of California’s U.S. Attorney’s Office details the scope of these charges:

According to his plea agreement, Baratov’s role in the charged conspiracy was to hack webmail accounts of individuals of interest to the FSB and send those accounts’ passwords to Dokuchaev in exchange for money. As alleged in the indictment, Dokuchaev, Sushchin, and Belan compromised Yahoo’s network and gained the ability to access Yahoo accounts. When they desired access to individual webmail accounts at a number of other internet service providers, such as Google and Yandex (based in Russia), Dokuchaev tasked Baratov to compromise such accounts.

According to his testimony, Baratov placed ads for his services on Russian-language websites. Once contracted, he gained access to his victims’ accounts by spearphishing them with faked correspondences designed to appear as though they were sent from the relevant email host.

Baratov pleaded guilty to one count of conspiring to violate the Computer Fraud and Abuse Act and eight counts of aggravated identity theft.