In Agatha Christie's "And Then There Were None," ten guests are invited to an island. When they arrive there, it turns out that each of the quests has been invited because they have committed a terrible crime and have managed to get away without being punished for that crime. Dr. Edward Armstrong is one of these guests. His crime was to cause the death of a patient by operating on her while he was drunk. Like all the other guests, Armstrong dies on the island. Armstrong dies by being thrown into the ocean from a cliff.
I forgot to provide my reference. It is right here: http://www.enotes.com/topics/then-there-were-none
One of my favorite books, And Then There Were None, is a wonderful story on how ten murders are forced to face the crime they had committed in the past. Trying to justify what they have done and be presented in good light in front of the society, each character in the novel tries to make out their situation in a way that makes them not see at fault. They don't want their status to be affected, so of course they are not going to admit to such crimes.
The crime Dr. Armstrong committed, as mentioned in the above answer, was murdering someone during an operation. Although accidents in surgery and in medicine occasionally do happen, Dr. Armstrong was drunk for this specific incident. That's a huge no no in the medical field. If he hadn't been drunk during the operation, perhaps the death could've been blamed on complications in the procedure, or how the patient reacted to certain movements and medicine. However, when you add alcohol into the equation, everything changes. Not only in this novel, but in real life too. For instance, a drunk driving accident is much more severe and illegal than your standard car accident. What Dr. Armstrong did, and reluctantly admitted, was an act of crime that society should not ignore. That is why Owen invited him to the island in the first place. To force him, and the rest of the group, to face the their committed crimes head on.