By Mark Simpson
BBC Ireland correspondent
Sir Hugh Orde has been looking for a new job for some time
Whoever replaces Sir Hugh Orde as head of the police in Northern Ireland will have to be a quick learner.
The security threat is at its highest level for a decade, and it is likely that the next chief constable will be a senior officer parachuted in from England.
Mind you, behind the scenes, in policing and political circles, some tentative preparations may already have been made.
It has been known for some time in Belfast that Surrey-born Sir Hugh was looking to get back to London.
Only this week, he spoke in a BBC Radio Ulster interview about his hopes of becoming president of the Association of Chief Police Officers (Acpo).
In the same interview, he was asked to choose his favourite music. The first song he chose was Bruce Springsteen's Born to Run.
Given what has now happened, it could be argued it was an appropriate title.
So is Sir Hugh running away as the job suddenly gets really tough?
Quite the opposite. He had decided long before the recent killings in Northern Ireland that it was time to move on.
Police officer Stephen Carroll, 48, and soldiers Mark Quinsey, 23, and Patrick Azimkar, 21, were killed in March. Sir Hugh decided last year to look for another job.
He applied for the job of Metropolitan Police Commissioner, got down to the last two, but was pipped by Acting Commissioner Sir Paul Stephenson, who was appointed in February.
He then went for the Acpo presidency and got it.
Given the three recent murders, a number of politicians may have tried to persuade Sir Hugh to withdraw his application.
The threat of more attacks is high, and some believe that when it comes to the top job in policing in Northern Ireland, it is no time for a rookie.
Sir Hugh, 50, has 30 years of policing experience, including seven in Belfast.
He is generally popular inside and outside the force, and has managed to steer his way through the minefield of Northern Ireland politics without too many gaffes.
Suddenly, the security situation in Belfast is back in the national - and international - spotlight and the chief constable of the Police Service of Northern Ireland (PSNI) is seen as the key figure when it comes to keeping the peace.
The security situation is back in the spotlight following three murders
But Sir Hugh has faith in his policing colleagues, and it would be a surprise if he doesn't have a successor in mind, or at least know a few strong candidates.
One well-placed political source said: "Come September, when he goes, it'll be a case of 'as we were'.
"We'll still have an experienced officer in charge of the PSNI, it'll just be a different face. It will probably be someone who is a chief constable or deputy in a reasonably large force in England."
The reason no-one is talking about successor coming from the ranks of the PSNI is that under the existing rules, none of the current assistant chief constables meets the experience criteria, and the current deputy chief constable, Paul Leighton, is due to retire this year.
That means Sir Hugh's successor will have to come from another force in the UK, or the Republic of Ireland police service, the Gardaí.
Given the large pool of senior officers in England, the most likely scenario is that someone from there will get the job.
It will be interesting to see what level of interest the post will generate.
Dealing with the dissident threat will obviously be a priority for the new chief constable, but there are many other issues to be tackled in terms of internal reform of the police service, concerns over the police budget and investigating hundreds of unsolved murders from the Troubles.
Then there is the political tightrope to be walked with Northern Ireland's rival politicians.
Sir Hugh was appointed PSNI chief constable in 2002
How can you keep unionists and nationalists happy at the same time?
How do you handle contentious marches? What about the move towards policing and justice powers being devolved from Westminster to Stormont?
On top of all that, there's the media scrutiny, and the constant public attention.
Sir Hugh Orde said this week: "You are absolutely in the public eye 24 hours a day.
"There is no such thing as a day off, even when you are 'off'."
Given the difficulties of keeping the peace, it is perhaps little wonder that another of Sir Hugh's favourite songs is Bridge over Troubled Water.
Oddly, he preferred it sung by Johnny Cash rather than Simon and Garfunkel.
Not everyone will approve of his choice of music, but most would agree that as chief constable, and as a bridge between Northern Ireland's divided communities, he is a hard act to follow.