Sinead Iona Fleming was a human born in Ireland in 1905. She married Branwell Damien Fleming. He later murdered her in the locked library at a party at their house on Fleming's Island in 1930, speculated to be a complex plan by Fleming to steal her money.
The mystery remained unsolved until the Fifth Doctor and his companions arrived on the Island and faced the I, the Doctor realising that one of the windows in the library had been rigged so that it could be discreetly opened from outside. (AUDIO: Iterations of I)