Dennis Mahon was convicted of three felonies related to the mail bombing of a city diversity office that injured its director and two other employees.
His twin brother, Daniel Mahon, was acquitted of a felony count of conspiring in the bombing plot. The judge ordered him to be set free.
The mixed verdict is a blow for federal authorities, who spent years investigating the two men. Agents with the US Bureau of Alcohol, Tobacco, Firearms and Explosives finally had enough cause to arrest the brothers in 2009 but the investigation continued even after that, totaling eight years in all.
