Vicars had at least one staunch ally: his cousin, the writer Sir Arthur Conan Doyle, whose Sherlock Holmes novels had made him a household name. Doyle contacted his cousin and offered to do whatever he could to help.

Doyle may have been the creator of fiction’s greatest detective, but he brought “nothing of practical value” to the investigation, said broadcaster and historian Myles Dungan, author of The theft of the Irish crown jewels: an unsolved crime. Instead, Doyle’s involvement was limited to review crime scene maps and support the Vicars during the ordeal.

The investigation has gone cold

Authorities apparently made very little progress in identifying the culprit, although investigators included the Dublin Metropolitan Police and Scotland Yard.

Not everyone involved was a professional investigator. A group of spiritualists conducted a seance and claimed the jewelry was hidden in a nearby cemetery. Authorities followed the trail but found nothing.

A viceregal commission, created in January 1908, did not fare much better. Instead of subpoenaing witnesses or investigating the crime itself, the commission focused on the Vicars and put the blame squarely on his shouldersaccusing him of negligence.

Disgraced, Vicars lost his position at Dublin Castle and the crime remained unsolved.

The mystery has given rise to several theories

Although the investigation failed to solve the crime, Vicars had his own theory. The person behind the theft, he insisted, was a man named Francis Shackleton.

A fixture of London and Dublin high society, Shackleton –– the younger brother of Arctic explorer Ernest Shackleton ––served as Dublin Heralda position in the Vicars’ office. Furthermore, Shackleton Apparently I had money problems that a cache of extravagant jewels could have solved.

Shackleton thus had easy access to the jewelry and, perhaps, even a mobile. But he also had an alibi: Shackleton was not in Dublin when the Vicars realized that the jewels were missing.

Other theories centered on the political climate of Ireland in the early 20th century, when the country’s nationalists were calling for “Home Rule” or for Ireland to have self-government. British King Edward VII I wondered if the Irish nationalists had stolen the jewels in a targeted and anti-colonial heist.