Poisoned Jokes

Banto's husband died after six months of marriage: The post-mortem report declared that he had died of eating poisoned mushrooms.
Some months later Banto got married again. Alas! A few months later the second husband died too.
The post-mortem report declared that he had died of eating poisoned mushrooms.
Poor Banto! She had to get married again.
After almost a year the third husband died!
He died of head injuries, because he refused to eat poisoned mushrooms.

The great nephew of Harry Houdini's wants to exhume the magician’s body to determine if he was poisoned.

If Houdini was poisoned, I would like to know four things: 1) Who is responsible? 2) Can that same poison be used on David Blaine? 3) Can the poison also be used on Criss Angel & David Copperfield? and finally, 4) Can I use the poison on every single magician, mind reader, and Circus Soleil performer in the Northern Hemisphere?