A Portland man was indicted by a federal grand jury Wednesday on charges he mailed threatening letters to Gov. Paul LePage, members of the U.S. Congress and Wisconsin Gov. Scott Walker, according to the U.S. Attorney’s Office.

According to the indictment, Michael R. Thomas, 51, mailed threatening letters to LePage and Walker, and U.S. Sen. Joe Lieberman, ID-Conn., and  U.S. Rep. Steve King, R-Iowa. He was also charged with illegally possessing a firearm, interstate stalking and making a terrorist hoax.

For nearly five years, Thomas sent threatening and harassing letters to a person in Massachusetts and sent an envelope containing white powder through the mail to a Massachusetts address, according to the indictment.

Thomas possessed a firearm after he was barred from doing so because he was convicted of a felony, the indictment said.

If convicted, he faces a maximum of 10 years in prison for allegedly threatening members of Congress, as well as on the firearm possession charge and Internet stalking. He faces a maximum of five years for allegedly threatening the two governors through the mail and for allegedly creating a terrorism hoax, according to the U.S. Attorney’s Office in Portland.

An investigation conducted by the Federal Bureau of Investigation and the Danvers, Mass., Police Department led to the indictment.