The Government has announced the promotion of Deputy Commissioner Fachtna Murphy to the post of Garda Commissioner.
He will assume the position when the current Garda Commissioner, Noel Conroy, retires in November.
The appointment was proposed by Minister for Justice Brian Lenihan and approved at yesterday's Cabinet meeting.
Mr Murphy was regarded as the favourite to take over from Mr Conroy, who is retiring on age grounds.
However, the timing of yesterday's decision caught many by surprise because Mr Conroy still has almost three months to run in his term.
Traditionally, an announcement is made closer to the retirement date of the outgoing Garda Commissioner.
Announcing the decision, Mr Lenihan offered his congratulations to Mr Murphy, whom he said had given many years of service to the Garda and had been committed to the "ongoing changes in recent times".
He said that since July 2003, Mr Murphy had been Deputy Commissioner with responsibility for all operational policing.
In that role, all of the Garda's 12 Assistant Commissioners had reported directly to him.
"He has been responsible for key operations, such as Operation Anvil targeting gangland crime and I am sure his commitment to these successful operations will continue in his new role," Mr Lenihan said.
Mr Murphy's promotion comes ahead of a period of personnel changes among the ranks of senior Garda management.
As well as Mr Conroy's retirement in November, Deputy Commissioner Peter Fitzgerald's retirement is also imminent.
The Government moved last year to extend Mr Murphy's time in the force by two years in order that three such senior officers would not retire in close succession.
If the two-year extension had not been granted Mr Murphy would have retired last June, at the age of 60.
However, the two-year extension meant that he could stay on until June 2009.
The Cabinet agreed yesterday to further extend his term in the force in a move which will see Mr Murphy staying on as Garda Commissioner until at least November 2009.
The Cabinet is expected to revisit the issue and a further extension is a possibility.
Mr Murphy's appointment was announced after he met Mr Lenihan and Taoiseach Bertie Ahern at Government Buildings yesterday afternoon.
Mr Murphy holds a BA in police management and a diploma in management and industrial relations.
Deputy Commissioner Martin Callinan was seen as Mr Murphy's main rival for the Garda Commissioner's post. He is currently responsible for strategy and change management across the force.
Regarded as a very bright officer, he will now most likely move to Mr Murphy's current position as Deputy Commissioner in charge of operations.
Fine Gael's spokesman on justice Jim O'Keeffe TD paid tribute to Mr Conroy.
He said that the outgoing commissioner had distinguished himself at many levels within the force at a time of great change in policing and across Irish society generally.
He also offered his congratulations to Mr Murphy.
"Crime remains an issue of huge importance for everyone in Ireland, and Fachtna Murphy will face a major challenge in tackling the issues linked to that crime," he said.