prosecutor baytieh knew it did not.in 1994. lots of suspicion, but no direct evidence that paul killed linda. and, baytieh felt, their prime suspect, a self-proclaimed genius, knew that. >> he was smart enough to realize that any police officer, a minute after she's murdered is going to expect the husband to be the suspect. he was one step ahead. >> reporter: baytieh's theory? paul tested different poisons, carefully picked an obscure one, then poisoned himself to cover his tracks. >> the first time linda got sick, he had the exact same symptoms because that allows him to say, "hey, look, we both got sick. maybe we both caught something." >> reporter: you think that's him thinking ahead? >> sure. that's his m.o. >> reporter: baytieh went back to the night linda died and the nicotine that killed her. he consulted a nicotine expert who had looked into the case back in 1994. >> he goes, "yeah, i remember the case. nobody ever followed up with me. i go, "would you kindly please be willing to write a report to us about your