ITV The Investigator: A British Crime Story Catch up on the ITV Hub Investigative journalist Mark Williams-Thomas re-examines police investigations that had previously been closed. 3 episodes available to watch Share this programme: Share on Facebook Share on Twitter Share on Google+ Series 2 Latest Episode 3 Thu Thursday 19 Apr 9pm Documentary series. Could the investigation into Angus Sinclair have a final twist? Episode 2 Thu Thursday 12 Apr 9pm Explosive documentary series. Mark Williams-Thomas investigates three brutal 1977 murders. Episode 1 Thu Thursday 5 Apr 9pm Mark Williams-Thomas begins his investigation by exploring the case of Louise Kay.