Legal Alien: A Scotsman in Montreal

Friday Fun

Another double-header:

Is it likely or unlikely that most professional tennis players have more than the average number of arms for humans?

And another one about poison (cos I know how much y'all loved the last one)

Legendary Madadian mass murderer, Shorty, was confessing to one of his unknown crimes, whilst on his death bed. He explain how he managed to poison someone by sharing an Apple with them. It was the victims apple and the victim had the free choice of which half of apple either he or Shorty ate, yet the victim died of poisoning after eating his half of the apple that Shorty had sliced. There was no swapping of apples nor was the poison administered to the victim in any other way and there was no known antidote for the poison.

How did Shorty manage to poison the victims half of the apple only?