A Canadian accused by the United States of helping Russian intelligence agents break into email accounts as part of a massive 2014 breach of Yahoo accounts is expected to plead guilty next week, according to court records.

Karim Baratov, who earlier this year waived his right to fight a U.S. request for his extradition from Canada, is

scheduled to appear in federal court in San Francisco on Tuesday for the plea hearing, according to a court calendar seen on Friday.

Baratov, a 22-year-old Canadian citizen born in Kazakhstan, was arrested in Canada in March at the request of U.S. prosecutors. He later waived his right to fight a request for his extradition to the United States.

Andrew Mancilla, Baratov's lawyer, declined to comment. A spokesman for the U.S. Attorney's Office in San Francisco did not respond to a request for comment.

The U.S. Justice Department announced charges in March against Baratov and three other men, including two officers in Russia's Federal Security Service (FSB), for their roles in the 2014 theft of 500 million Yahoo accounts.

Verizon Communications Inc, the largest U.S. wireless operator, acquired most of Yahoo Inc's assets in June.

Prosecutors said that the FSB officers, Dmitry Dokuchaev and Igor Sushchin, directed and paid hackers to obtain information and used Alexsey Belan, who is among the U.S. Federal Bureau of Investigation's most-wanted cyber criminals, to breach Yahoo.

When the FSB officers learned that a target had a non-Yahoo webmail account, including through information obtained from the Yahoo hack, they worked with Baratov, who was who paid to break into at least 80 email accounts, prosecutors said.

The individuals associated with the accounts they sought to access included Russian officials, the chief executive of a metals company and a prominent banker, according to the indictment.

At least 50 of the accounts Baratov targeted were hosted by Google, the indictment said.

Tuesday's proceedings before U.S. District Judge Vince Chhabria are scheduled as a "change of plea" hearing.

Baratov, the only person arrested to date in the case, previously in August pleaded not guilty to conspiring to commit computer fraud, conspiring to commit access device fraud, conspiring to commit wire fraud and aggravated identity theft.