(Reuters) – A federal grand jury in California has indicted a Russian man for hacking computers belonging to LinkedIn, Dropbox and Formspring, the U.S. Justice Department said on Friday.

Yevgeniy Nikulin was arrested on Oct. 5 by officials in the Czech Republic and remains in custody in Prague, the Justice Department said in a news release.

LinkedIn said at the time of his arrest that it was related to a 2012 breach at the social networking company that may have compromised credentials of 100 million users, prompting a massive password reset operation.

It was not immediately clear if U.S. officials had begun extradition proceedings to have Nikulin, who was indicted on Thursday by a federal grand jury in Oakland, California, brought to the United States to stand trial.

According to the DOJ, Nikulin is accused of accessing computers belonging to LinkedIn, Dropbox and Formspring and obtaining information from them.

The U.S. attorney’s office could not immediately be reached for further comment. It was not yet clear who would be representing Nikulin in the proceedings.

He is also alleged to have used credentials of LinkedIn and Formspring employees in connection with the computer intrusions. Further, Nikulin is alleged to have engaged in a conspiracy with unnamed co-conspirators to traffic stolen Formspring user credentials.

The indictment charges Nikulin with three counts of computer intrusion, two counts of intentional transmission of information, code, or command causing damage to a protected computer; two counts of aggravated identity theft; one count of trafficking in unauthorized access devices; and one count of conspiracy.

(Reporting by Eric Beech in Washington and Dan Whitcomb in Los Angeles; Editing by Eric Walsh and Diane Craft)