Could he have been given small amounts of arsenic over a long period of time?
I'm not up on my poisons. Can't they look at his hair to see if arsenic has been ingested and how long ago it was ingested? Kind of rings on a tree tell its's age.
People who are poisoned with arsenic usually get it in increments;someone will put it in their food or drink.
I watch forensic programs and there have been several cases in which someone was slowly poisoned with arsenic.(These are real programs,mind you,not CSI).
They examine strands of hair to see how much arsenic has been injested. I believe a Gas Chromatograph Mass Spectrometer is used in this case.
The gas chromatograph is used to separate and analyze compounds that can be vaporized without decomposition.
I love forensic programs. I learn so much from them. Who says TV rots your brain?