Jo Lupo (Erica Cerra)Deputy Jo Lupo is Sheriff Jack Carter's right-hand woman in Eureka, a community in the Pacific Northwest planned by President Harry S. Truman as a place for America's most brilliant minds to work on breakthroughs in science.She is a physically and mentally tough, with a no-nonsense approach to life and law and order. She is a lover of weaponry and is the owner of many guns. She often brings ones to situations that most others would consider them unnecessary.She and Sheriff Carter occasionally butt heads due to their differing approaches to law and order but they make a strong team.Jo has a short fuse and is often exasperated at the predicaments created by the nutty professors of Eureka but they appreciate how she looks after them.Jo was previously a special forces U.S. Army Ranger and is very strong for a woman of her stature, easily taking on male and female opponents.Her romantic life is less fulfilling although there is at least one man Jo appears to have interest in.Incongruously, Jo wanted to be a dancer as a child but the situation she grew up in was not conducive to the arts and a heavily male influence led her down her current career path.