Allan Mackenzie Nicol joined the Crown Office and became a Procurator Fiscal for 12 years. In 1993 he qualified as an Advocate and defended clients charged with serious offences until 2011, when he re-joined Crown Office and became an Advocate Depute, prosecuting in High Courts throughout Scotland. 

Allan has written several works on true crime including:
Manual: Scotland’s First Serial Killer, The Monster Butler: Inside the Mind of a Serial Killer, Liberation and Sheila Garvie: Mastermind or Victim