that's what linda's friend mary seibold thought all along. she said she shared her concerns with linda. >> let's have someone go into the house and just check it. let's see if there is anything foreign in here. >> but she says linda never took that advice. never had her home tested. now they all waited for the toxicology tests on linda's body. and sure enough, the lab that examined linda's samples did detect and identify something quite curious. linda curry's body contained lethal levels of nicotine, which only deepened the mystery because, according to everyone who knew her, linda curry did not smoke cigarettes or anything else. never had. >> never. never. >> did that make sense to you, nicotine poisoning? >> i had never heard of it. she never smoked. how could this happen? how could this be? no, i was shocked. i was shocked. >> is it unusual to find nicotine in someone's body? >> it's not unusual. we are exposed to nicotine either as a smoker or as a nonsmoker. >> there are more sources of nicotine than you think. besides cigarettes, there