The director general of the Northern Ireland Prison Service has said he intends to step down from his post before the end of this year.
Robin Masefield said he had advised Justice Minister David Ford of his decision.
The moves comes against a background of a series of controversies which have afflicted the high security Maghaberry prison.
Mr Masefield said it "has been a privilege to serve in this capacity".
On Thursday he said: "I had originally 'signed up' for five years from my appointment in December 2004, but was pleased to stay on to cover the transition at devolution.
"It has been a privilege to serve in this capacity and while it has been challenging and demanding, it has also been rewarding.
"I look forward to continuing to serve with the Prison Service for the remainder of this period, as there remains much important work to be done," he said.
Management within prisons in Northern Ireland has been heavily criticised in a series of reports by inspectors.
According the BBC NI Home Affairs Correspondent Vincent Kearney, on each occasion Mr Masefield responded by insisting he was the best man for the job.
Our correspondent said justice minister David Ford has signalled that reform of the prison service will be one of his key priorities - and finding a new head of the service will now be one his first major tasks.
On Thursday, the prisoner ombudsman paid tribute to Mr Masefield.
In a statement, Pauline McCabe spoke of the "incredibly high level of personal commitment and dedication" he had shown over the past five years.
The prison officers' association, which earlier this year issued a declaration of no confidence in Robin Masefield and his management team, said it did not want to comment on the announcement.