Mosgiel man, John Twaddle, says he always believed he knew who killed his brother in the Australian outback more than four decades ago.

Police arrested a former prison officer last week, in connection with the cold case murders: of Twaddle's brother Gordon, family friend Timothy Thomson, and Australian woman Karen Edwards.

While the arrest of the 63 year-old vindicated Twaddle's suspicions, it brought him little joy.

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