then she walked all the way home. over the next few days, police got a warrant for carter and david's cell phones. that camera app, so useful. >> well, we learned that they had conducted surveillance at ashlea's apartment weeks before that. they had a picture of her apartment. her actual door to her apartment, and they had pictures of her vehicle, the white dodge ram pickup. >> reporter: in early december, 2014, carter cervantez and david mallory were arrested and charged with the murder of ashlea harris. cold comfort for ashlea's sister. >> it's just such a loss and it's so pointless. i just don't understand how people could do that. >> reporter: they were tried separately, but the cases against them were virtually identical. assistant d.a. kevin rousseau led the prosecution.