>> i'd say extremely rare. >> reporter: cyanide is so deadly, bloom says, an amount the size of a baby aspirin can kill. but it's not supposed to be easy to get. >> the most likely place that you would find cyanide would be -- >> in medical laboratories and university laboratories. >> reporter: that could explain why authorities used search warrants and subpoenas to search the lab where klein's husband works. a source close to the investigation confirms cyanide was found in his lab. but neighbors say there was no indication of trouble in the home. >> she was very happy. she was very relaxed. >> reporter: dr. ferante's attorney says authorities are looking at his client. >> i'm sure what do they call it, person of interest or suspect. i don't think there's any doubt about that. >> reporter: pittsburgh authorities would not comment about whether he is the primary focus of suspicion, saying the investigation's being handled by homicide detectives, but no