One of the high-profile investigations headed up by John Caldwell was the murder of PSNI officer Ronan Kerr in the same town where the senior detective was gunned down.
The killing of his colleague Constable Kerr was blamed on dissident republicans styling themselves as the New IRA – the same renegade group police suspect of shooting Detective Chief Inspector Caldwell on Wednesday night.
Mr Kerr, a 25-year-old recently graduated police recruit, died when a booby trap bomb detonated under his car outside his home in Omagh in April 2011.
