Last night on Who Do You Think You Are? comedian, actor - and the man behind Mrs Brown – Brendan O’Carroll revisited a family story that had been shrouded in mystery for almost a century; the murder of his grandfather, Peter O’Carroll.

More CSI than genealogy, the episode set out to track down the truth behind the murder which took place in Peter’s locksmith shop in Dublin, in October 1920. The O’Carroll family had long believed the infamous Black and Tans to be responsible for the murder, however Brendan’s journey took him on a far more sinister path.

Peter was murdered late at night, shot in the head execution-style and then left with a note pinned to him that read ‘traitor to Ireland, shot by the I.R.A.’. This note, however, never rang true with the family, and the presence of prominent Irish nationalists confirmed Brendan’s suspicions that the note was a red herring, left by British forces to mask the nature of the killing.

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As Brendan’s investigations went on, he discovered that the likely murderer of his Grandfather was a member of the Royal Auxiliary Force, British troops notorious for their ruthlessness. Similarities between Peter’s murder and the murder of a Dublin Councillor, J.A. Lynch eventually led Brendan to his grandfather’s killer, a British Auxiliary officer named Jocelyn Lee Hardy.

A scan of our records reveals that we not only have the birth, marriage and military records of Peter’s murderer, but also the death record of Peter himself as well as newspaper reports both on Findmypast and the British Newspaper Archive with details of the murder.

Do you have any mysteries in your family history? Why not make a start on solving them today?