John Tomkins of Dubuque was indicted by a federal grand jury in Chicago late Tuesday, The Chicago Tribune reported.

Tomkins was arrested in April. He allegedly sent threats to a number of companies and two explosive devices that had not been completely armed.

Both devices included warnings that they were one wire short of going off.

Tomkins allegedly used the name “The Bishop” on his communications. He became a suspect after investigators matched up stock ownership records with the apparent pattern of the threats.