A Connecticut man is facing sentencing for mailing threatening letters. Roland Prejean, formerly of Thomaston and Morris, is scheduled to be sentenced Friday in federal court in Bridgeport. In 2010, authorities said, Prejean mailed a letter claiming he had planted a hidden bomb on a remote timer in the Thomaston Post Office. The letter resulted in evacuations, but no explosive devices were found. Prosecutors said Prejean mailed a letter to a judge in New London that included a substance that was falsely represented to be ‘‘liquid anthrax,’’ and he sent threatening letters to a private individual and a probation officer. Prejean pleaded guilty to using the mail to communicate a bomb threat and mailing threatening communications. His lawyer said he has a history of severe mental illness.