a camera was rolling as prosecutor fran humphries began his case. >> so this is purely motive evidencech establishes a motive for richard gagnon to end the lives of these two people. >> reporter: as humphries recalls, the case against rick was always motivation strong, evidence weak. not much more than a drop of charlie parker's blood on a shoe when you came right down to it. even so, humphries told the court the blood put rick at the murder scene. >> reporter: but he had a story for it, didn't he? >> he did. it didn't -- it didn't hold water. but it -- he had a story about it. >> reporter: humphries recited rick's version of how blood got on his shoe. he had gone into the parker house to get a set of car keys, sometime after crime scene techs had finished up. >> he looked to his right, which was the window leading in to the bathroom where big charlie had died and noticed the blood. >> reporter: rick said he worried bambi, pacing outside, might look in the window and freak out all over again. >> he went in and stepped through the bathroom and closed the blind. >> reporter: "and whoops,

i didn't do anything wrong. >> but to prosecutor fran humphries, it made perfect sense. >> the motive is unavoidable in this case. bambi needed her stepfather and mother dead, so she could get her property back. >> property valued at north of $1 million. classic question people in your line of work poses, well, who benefited. >> bambi. >> as for bambi's boyfriend, rick, humphries believed bambi persuaded him to help carry out the murderous deed. but both rick and bambi said the prosecutor had it all wrong. they insisted they wouldn't do anything to harm charlie or diane. >> she wants the land. that is the most ludicrous thing ever. it was given to me by my daddy to begin with. even though it was in mama's name, if i wanted the land back, all i had to do is tell mama that. >> also, absurd she said, was the allegation she would kill her parents over disagreements about how to raise her boys. >> who does not have disagreements ever with their mother or their father. me and mama didn't always agree on the upbringing of cody and nate. but that doesn't mean i'm going to kill my mama because