DES MOINES, Iowa — An Ottumwa man in prison for robbery and burglary who once threatened to kill former President Barack Obama and a judge has now been indicted again on charges of mailing a death threat to a federal judge.

Matthew James Howard, who is serving 13 years in prison, received an additional three years in September 2013 for writing letters threatening to kill Obama and a judge earlier that year.

Howard, who is 31, has been indicted again for threatening U.S. Judge Linda Reade in a letter sent from prison in Anamosa in November. If convicted he faces up to 20 years more.

In the 2013 case the federal prosecutor said Howard has an extensive mental health history.

There was no attorney yet listed to represent him.