Marie Alexandrine Mary Freiin von Vetsera was born on 19 March 1871 as the third child and second daughter of Albin Freiherr von Vetsera (1825–1887), an Austrian diplomat from Pozsony, Kingdom of Hungary (present day Bratislava, Slovakia),[1] and his wife, born Eleni Hélène Baltazzi (1847–1925), member of a wealthy noble family from Chios, Greece (then part of the Ottoman Empire).

[citation needed] Freifrau von Vetsera's main goal was to advance socially, for which she had the support of the imperial family, even though she did not have the right to visit the court.

She wanted to break out from the parvenu status she had as the wife of a newly made noble,[6] and for this, she needed her daughters to marry into the best possible families.

[11] In 1888, Vetsera became infatuated with Crown Prince Rudolf (1858–1889), a married man 13 years her senior, after returning from Cairo following the death of her father.

In the dark room, he found the crown prince sitting motionless by the side of the bed, leaning forward and bleeding from the mouth.

[11] As her death was thought to be a suicide, her uncles had a hard time persuading the abbot to give permission for a Christian burial, eventually convincing him that she had only committed it because of momentary insanity.

After Soviet troops had disturbed Vetsera's grave, and when it was being repaired in 1955, the monks found a small skeleton inside the coffin, with no apparent bullet holes in its skull.

Holler claimed he petitioned the Holy See to inspect their archives of the incident, including records of the investigation by an apostolic nuncio, Archbishop Luigi Galimberti, who had found that only one bullet was fired.

Lacking forensic evidence of a second bullet, Holler advanced the theory that Vetsera died accidentally, probably as the result of an abortion, and that Rudolf then shot himself.

[21] Lucy Coatman, who is planning a biography of Vetsera, argues against this, citing a letter written by Mary shortly before the Mayerling incident.

[19] In 1991, Vetsera's remains were disturbed again, this time by Helmut Flatzelsteiner, a Linz furniture dealer obsessed with the Mayerling incident who removed them for a forensic examination at his expense, which took place in February 1993.

Forensic experts found the bones were indeed 100 years old and those of a young woman aged around 20, but since part of the skull was missing, it could not be determined if there had ever been a bullet hole.

[23] On 31 July 2015, the Austrian National Library obtained copies of Vetsera's farewell letters to her mother and other family members which had been found in a bank safe deposit box, where they had been placed in 1926.