tandy cyrus says hillary had a motive to murder her son. elizabeth vargas there are people who say now that the reason you and tandy broke up was because garrett wanted you out of the house. nick hillary not true. elizabeth vargas there wasn't tension between you and garrett? nick hillary no. grfx (3.5 secs) but look at these text messages tandy sent nick. "i've been waiting for almost a year for the situation between easy for me but i have to put my kids first?" and prosecutors say that's nick's car following garrett on his skateboard, riding out of his school's parking lot minutes before his murder -- (6.5 secs) but nick says he didn't see garrett and was simply there to scout a soccer game but left at half time because it was raining. william fitzpatrick i don't believe that nick hillary was in that parking lot by coincidence. he was hunting garrett. district attorney bill fitzpatrick argues nick strangled garrett in his mother's ber out this back window to escape. elizabeth vargas: so no fingerprints, no dna, no hairs, no fibers. really

. >> reporter: tandy cyrus says hillary had a motive to murder her son. there are people who say now that the reason you and tandy aren't together was because garrett wanted you out of the house. >> not true. >> reporter: there wasn't tension between you and garrett? >> no. >> reporter: look at the text messages tandy sent nick. i've been waiting for almost a year for the situation between you and my kids to get better and it's not. this is not easy for me. but i have to put my kids first. that's nick's car following garrett on his skateboard. riding out of his school parking lot minutes before his murder. but nick says he didn't see garrett, and was simply there to scout out a soccer game and left at halftime because it was raining. >> i don't believe that nick hillary was in the parking lot by coincidence. he was hunting garrett. >> reporter: the district attorney argues nick strangled garrett in his mother's bedroom and then jumped out this back window to escape. hairs, fibers, really nothing. >> right. >> reporter: police found no dna, nothing to prove