They departed the programme when O Mongain became the news station's Deputy Foreign Editor and Brian Downing left journalism after a long career in print and broadcasting to become Head of Editorial Standards and Compliance in RTE.
Other presenters in the past included the national broadcaster's former Middle East Correspondent Richard Crowley, Michael Good, Paul Maguire, Gavin Jennings and Sean O Rourke.
David McCullagh previously worked on the programme in the 1990s prior to becoming a dedicated political reporter.
The citation, published on the Law Society website, read: "An excellent example of detailed investigative reporting, bringing previously unpublished information to the public attention and providing incisive analysis of the difficulties involved".
Lengthened editions are also aired on the occasion of major breaking news stories such as general elections or referendums.