insisting police had it all wrong? a security video was about to clear things up, and reveal a potential motive. here again is keith morrison. reporter: it was late saturday morning, the day after black friday. 25-year-old carter cervantez was talking to detectives and lying though her teeth. i know what i did this morning. i know where i was. i know where i went. reporter: detective cedillo certainly knew where she went the hulen mall. but she kept insisting she d been at home all morning. you re about to make the biggest mistake of your life. do you understand me? reporter: and she still wouldn t confess to it? she wouldn t budge. i got up, i went and put the laundry in, and i went and checked my e-mail. that s all. you found me in my apartment complex. reporter: then when the detectives stepped out of the room, she did something interesting maybe incriminating. she took a drink, puts the bottle down. she picks it up again and before
it was late saturday morning, the day after black friday. 25-year-old carter cervantez was talking to detectives and lying though her teeth. i know what i did this morning. i know where i was. i know where i went. reporter: detective cedillo certainly knew where she went the hulen mall. but she kept insisting she d been at home all morning. you re about to make the biggest mistake of your life. do you understand me? reporter: and she still wouldn t confess to it? she wouldn t budge. i got up, i went and put the laundry in, and i went and checked my e-mail. that s all. you found me in my apartment complex. reporter: then when the detectives stepped out of the room, she did something interesting maybe incriminating. she took a drink, puts the bottle down. she picks it up again and before
clear things up and reveal a potential motive. here again is keith morrison. reporter: it was late saturday morning, the day after black friday. 25-year-old carter cervantez was talking to detectives and lying though her teeth. i know what i did this morning. i know where i was. i know where i went. reporter: detective cedillo certainly knew where she went the hulen mall. but she kept insisting she d been at home all morning. you re about to make the biggest mistake of your life. do you understand me? reporter: and she still wouldn t confess to it? she wouldn t budge. i got up, i went and put the laundry in, and i went and checked my e-mail. that s all. you found me in my apartment complex. reporter: then when the detectives stepped out of the room, she did something interesting maybe incriminating. she took a drink, puts the bottle down. she picks it up again and before she can take the second drink, she stops mid-air, spills water on herself. puts the bottle dow
reporter: detective cedillo certainly knew where she went the hulen mall. but she kept insisting she d been at home all morning. you re about to make the biggest mistake of your life. do you understand me? reporter: and she still wouldn t confess to it? she wouldn t budge. i got up, i went and put the laundry in, and i went and checked my e-mail. that s all. you found me in my apartment complex. reporter: then when the detectives stepped out of the room, she did something interesting maybe incriminating. she took a drink, puts the bottle down. she picks it up again and before she can take the second drink, she stops mid-air, spills water on herself. puts the bottle down and just stares at it for about 10 to 15 seconds. she then reaches over and grabs a tissue from the table and starts wipin down the bottle and then wipes down the mouthpiece. reporter: what did that say to you? well, that she was afraid that we were gonna obtain her dna from the bottle. reporter
reporter: it was late saturday morning, the day after black friday. 25-year-old carter cervantez was talking to detectives and lying though her teeth. i know what i did this morning. i know where i was. i know where i went. reporter: detective cedillo certainly knew where she went the hulen mall. but she kept insisting she d been at home all morning. you re about to make the biggest mistake of your life. do you understand me? reporter: and she still wouldn t confess to it? she wouldn t budge. i got up, i went and put the laundry in, and i went and checked my e-mail. that s all. you found me in my apartment complex. reporter: then when the detectives stepped out of the room, she did something interesting maybe incriminating. she took a drink, puts the bottle down. she picks it up again and before she can take the second drink, she stops mid-air, spills water on herself.