On 30 January 1889, Crown Prince Rudolf, heir to the throne of Austria-Hungary was found dead alongside his mistress, 17 year old Mary Vetsera at The Mayerling, an isolated hunting lodge.
At first it was announced that he had died of natural causes, most likely heart failure. Mary's death was kept secret, but not for long.
The official investigation that followed concluded that both Rudolf and Mary had died of gunshot wounds in what appeared to be a suicide pact.
The Emperor Franz Joseph now ordered all inquiries to cease.
Rudolf did not get on with his father, he was was liberal who associated with radicals and lent his support to those who demanded reforms.
He was a heavy drinker who frequented, clubs, brothels, neglected his wife and was heartily disliked at the Imperial Court for his outspoken views and discourteous manner.
He was also considered a liability by Austria's German ally without whose support the Empire would struggle to survive.
As the only son of the Emperor the Crown would now pass to Franz Joseph's brother Karl Ludwig but he renounced it in favour of his son the Archduke Franz Ferdinand.
No more liked than Rudolf he was at least a sober and level-headed man who took his responsibilities seriously, and his assassination on 28 June 1914, would prove the catalyst for war.
At Rudolf's funeral the Imperial Family remained barely fifteen minutes.
Was the Mayerling Incident a suicide pact? Or was it a politically motivated murder? Certainly many of Rudolf's relatives believed it was the latter.
Either way it remained a convenient death.
Crown Prince Rudolf
Mary Vetsera, Crown Prince Rudolf's 17 year old mistress.
Crown Prince Rudolf and Princess Stephanie, the wife he later ignored on the day of their engagement.