. >> remember, josh armstrong, a.j.'family home. >> josh had access to the house just like a.j. did. in fact, josh showed up at the scene the night this happened. >> the alarm was activated. the house was secured. there was no forced entry anywhere, so how could josh have gotten in and done this and left? >> josh's hands were also tested for gunshot residue the night of the murder, but they came back clean. houston police ultimately ruled out josh as a suspect. >> what they didn't know was josh's psychiatric history that was coming. >> the defense puts forth the fact that josh armstrong has been suffering from mental illness. >> the defense tried but was unable to submit josh's medical records as evidence, so they call younger sister kayra to testify about what they say was really going on in the armstrong home. >> nothing could ever be said that would make me believe that a.j. killed our parents. >> she was in the house every day, day-to-day. she saw a.j. and she saw josh. >> kayra said when josh came back from college,