Who killed Cara Jo Roberts?

Don Bradley has a report on the first anniversary of the Cara Jo Roberts murder. Roberts was a young mother from Harrisonville who was found slain in her bathtub. Friends and family have raised a huge reward for leads in the case -- $22K, according to this site -- but investigators have hit a brick wall. Don's story mentions one theory that's been kicked around, but investigators don't believe that's why Roberts was murdered.