The Associated Press reports that a formal investigation has been launched to determine if an Oregon election worker tampered with today's election.
The AP identifies the suspect as 55-year-old Deanna Swenson of Oregon City.
Oregon's Department of Justice confirms that it has begun a criminal investigation after witnesses said they spotted Swenson filling in Republican ovals on ballots where preferences had been left empty by voters. All of Oregon's vote is conducted via mail.
An Oregon County election official said Swenson had worked in prior elections.
An attorney representing the county said at least two ballots "are highly suspect" and state investigators are looking through other ballots that Swenson handled to determine if tampering was more widespread. The ballots in question are now officially evidence and will not be released in time to be counted for today's election.