>> we did. >> remember, gavin is chris and jennifer davis' son.hael collapsed. >> the investigators said, "did she ever borrow insulin from you?" and that's when jennifer's like, "yeah, she needed it when she had cancer and -- and she got sick." and then that's when they were like, "you know when?" i felt like at that moment we both were like, oh, my goodness. 'cause now we know that she's a thief and a fraud. >> when we started seeing the text messages with jennifer davis about insulin, it was very revealing. if you believe the previous things that natalie has said, she should have already had insulin readily available in the home. so it made no sense to go through all this effort. i think it's clear that she poisoned him with insulin. >> authorities develop a theory of how natalie may have used insulin to kill michael. >> when he's finally taken to the emergency room, he presented with a blood sugar level of 21, and he's not diabetic. >> you get low blood sugar by receiving too much insulin. natalie had access to insulin. she had the means to in