The California Supreme Court on Wednesday ordered Riverside County Sheriff Chad Bianco to stop his investigation into ballots from the November special election that his office seized following accusations of voter fraud.

Bianco, who is also running as a Republican candidate for governor, seized more than 650,000 ballots from the local election office as part of his investigation, which began in February. The sheriff followed a tip from a local community group that claimed the vote tallies did not match the official number of ballots cast.