>> as police canvassed the neighborhood for leads and witnesses, the investigator also had to consider the perpetrator may have been someone julie knew. >> you're not ruling anyone out or in. you're simply going through the motions. you're speaking to the immediate family first. working your way out. >> the sheriff's department did not tell the griffiths julie had been murdered. >> we were not told anything by the police at that point. >> but anyone at the scene might have guessed foul play was somehow involved. >> there was just cops all over the property. >> you said, why the cops? >> exactly. yep. >> naturally the first person detective carter interviewed was julie's husband, keith. >> first of all, we are sorry for your loss. >> appreciate that. >> at first, keith talked about what everyone perceived was the cause of the inferno, an accidental fire set off by a new newly installed heating unit. >> you had it installed tuesday? >> it was a whole new system.