MADISON, Wis. -

A federal grand jury in Madison has indicted a Superior man with sending threatening letters laced with white powder to a man and his wife.

A grand jury indicted 62-year-old Gerald Johnsted in 2012 with two counts of sending threats via the mail to a man identified only as B.D. and his wife in 2009 and 2010.

Another grand jury on Wednesday added two new counts to the indictment accusing Johnsted of including white powder in the letters he falsely portrayed as a weapon of mass destruction.

Johnsted faces up to 20 years in federal prison if he's convicted on all four counts. His attorney, Stephen Jon Meyer, didn't immediately return a message.