child, i would imagine, much less? >> no! she always wanted to be a mother, to have a family. she would not throw it away like that. >> as they eliminated all of the other possibilities, the detectives, along with doctor lapointe came to a sinister conclusion. >> i am proceeding like this is unintentional poisoning until proven otherwise. >> why would somebody choose thallium? >> someone would choose thallium, because it looks like a medical disorder. it presents as someone having a slow decline, and withering away, dying. you would associate this with a chronic illness. it is poison, to get away with it. >> the next step to solving this mystery was figuring out how brigida had been poisoned. doctor lapointe did his own kind of detective work. >> and, you see this kind of, really bright spots everywhere, all throughout. >> these little white flex? >> the little white flecks are thallium ian brigida's deduct -- digestive tract. >> when you see this.