An Oklahoma man was sentenced Tuesday to seven years in prison after he was convicted of mailing an inoperable homemade bomb to Maricopa County Sheriff Joe Arpaio.  

U.S. District Judge Neil Wake said the vendetta carried out by Gregory Lynn Shrader of Jay, Oklahoma was a calculated act of evil.

Authorities said Shrader wasn't motivated by animosity toward Arpaio, but instead sent the bomb in hopes of framing his former partner in a financial trading books business by listing the former partner's name on the return address.

Prosecutors alleged Shrader dropped off the package in April 2013 at a U.S. Postal Service collection-box unit in Flagstaff. Investigators say Shrader drove with a relative from his home state to Arizona to put the bomb in the unit and that Shrader was driven by a need for revenge against his former partner.

The former partner had denied sending the package.