Reuters reports Derrick Callella, 42, pleaded guilty in federal court to two counts of harassment by telecommunications device, marking the only criminal conviction to date stemming from the disappearance of 84-year-old Nancy Guthrie from her home in Tucson, Arizona, five months ago. The guilty man was arrested back in February and charged with making a false ransom threat in the U.S. District Court of Central California. He was released from custody after posting a $20,000 bond.