crime scene investigators found human blood around some new mulch at the home of kathleen dorsett. him grapes now refused to talk. >> do you wish to? >> no. >> reporter: prosecutor marc lemieux had the blood, along with the reports of screaming on the morning stephen disappeared, and the bad history between kathleen and stephen. but he wanted to nail down the details of the case -- so he let her leave the station. >> we did not charge her yet and the reason for that is we wanted to sit back and figure out was there more to this story. >> reporter: two days later, they made a decision. with police cameras rolling, the investigation team went back to kathleen's home. >> i remember walking up to the door and knocking on the door. >> thomas had answered it and invited me in. i told kathleen that she was under arrest for the murder of stephen moore. she was handcuffed and she was quickly escorted from the residence. >> reporter: the neighbors watched, flabbergasted, as kathleen dorsett, teacher, devoted mother, and daughter of a nice respectable couple, was arrested for the murder of st