A Romanian computer hacker who revealed the existence of a private email server used by Hillary Clinton when she was secretary of state is expected to plead guilty to hacking-related offenses, a U.S. law enforcement official said on Tuesday.

Accused hacker Marcel Lazar, who used the alias "Guccifer," is scheduled to enter a guilty plea at a hearing early on Wednesday before Judge James Cacheris in U.S. District Court, Alexandria, Virginia, said the official.

He was indicted on charges including wire fraud, unauthorized access of a protected computer, aggravated identity theft, cyberstalking and obstruction of justice.