UNITED NEWS INTERNATIONAL (UNI) — A former National Guardsman has been sentenced to six months behind bars for threatening to kill Vice President Mike Pence.

On March 9, 23-year-old William Dunbar was sentenced to six months in federal prison for threatening to kill Pence last fall at a Sept. 11 memorial service in Shanksville, Pennsylvania.

Dunbar was arrested by police three days before Pence’s speech.

Local police said that Dunbar was on duty at the Army National Guard Training Center, 90 miles from where the vice president was scheduled to speak, when he made repeated threats to kills Pence.

According to Secret Service interviews, Dunbar was known on base as violent and unpredictable.

The National Guard base would not allow him to be near guns and kept him under supervision.

Dunbar’s sentence also requires him to receive mental health treatment.