A 46-year-old man was sentenced Friday to 70 months in federal prison for sending a threatening note to a New London judge in September 2010 along with a substance he said was “liquid Anthrax” and making a bomb threat that resulted in the evacuation of the Thomaston post office.

Roland Prejean, also known as Gary Joseph Gravelle, pleaded guilty in January to one count of using the U.S. Mail to communicate a bomb threat and four counts of mailing threatening communications.

Prejean, who lived in Thomaston and Morris, has been in federal custody since he was arrested in North Dakota on Sept. 7, 2010, after mailing more than 50 threatening letters, according to the office of Acting U.S. Attorney Deidre M. Daly.

On Sept. 4, 2010, Prejean sent a letter to an unnamed Superior Court judge at the courthouse at 70 Huntington St. in New London. The letter contained a substance labeled “liquid Anthrax.”

“Hello. My name is Roland Prejean and I am the man who is going to kill you,” the letter began. Prejean went on to say that he had just spent six years at Connecticut Valley Hospital and that the judge had committed “wrongs against some of my people.”

Prejean also sent a threatening letter to the Thomaston post office claiming he had planted a hidden bomb there with a remote timer. The post office and a nearby school were evacuated as bomb technicians searched for explosive devices. Nothing was found.

At Friday’s sentencing, the government also presented evidence of more than 50 other threatening letters that Prejean mailed both prior to his arrest and while he was detained in federal custody.