The Deputy Chief Constable of Norfolk, Mr Colin Port, has been appointed to join the team currently investigating the murder of human right's solicitor, Ms Rosemary Nelson.
He will "direct, control and command" the day-to-day investigation, according to the RUC Chief Constable, Sir Ronnie Flanagan.
A spokeman for the Northern Ireland Office said Mr Porty "brings with him a wealth of experience, particularly in criminal investigations which will be valuable to the investigation".
The senior police officer will take day-to-day control of the inquiry into the killing. Ms Nelson was fatally injured two weeks ago when a booby-trap device exploded under her car. Loyalist dissident grouping, the Red Hand Defenders, later claimed responsibility.
Mr Port is due to arrive in Northern Ireland today to visit the scene, the incident room and the wider area.
The Chief Constable of Kent, Mr David Phillip, and FBI representatives, were appointed to oversee the case in the aftermath of the killing and their role is set to continue.