The fun thing is that only the dumb poisoners are the ones that usually get media attention. Exactly because they are dumb. The smart ones usually never get caught.

Consider someone with a medical degree (like myself). I not only know good and reliable ways to poison someone... I also have quite easy access to the substances. I can obtain some of them without registration. And I also know which substances will not be discovered by the lab when doing the routine post death tests (or ones that are not routinely tested). I am also quite aware which substances are not at all discoverable in my country. Also which ones could be made to look like flu, renal failure, pneumonia etc. Even worse.... If someone like me wants to kill some relative, they can wait for the right time to do it... for example, when the seasonal viruses have done their work (when they want to hide the poison symptoms somewhere amidst the virus symptoms). It will not even raise any suspicion at all...

Strange she should leave out the most interesting poisoning homicide in recent history, that of Alexander Litvinenko, in which the victim was not only condemned to "live in interesting times", but to die in an especially interesting way. The docs didn't figure out what was wrong with him until a few days before he died. But, once they did, Scotland Yard traced the radioactive trail all across Europe and back to the capital of the Evil Empire.

http://en.wikipedia.org/wiki/Poisoning_of_Alexander_Litvinen...