Northern Ireland's Victims' Commissioner Kathryn Stone is to leave her post for a new role in England - a decision she has described as the most difficult of her career.
The announcement of her unexpected departure comes just over 18 months after her appointment to the high-profile and politically sensitive position.
Ms Stone was advocate for the victims' sector during a period of on-going contention over how Northern Ireland deals with the legacy of its troubled past.
She came under fire last year after she declined to label the IRA and UVF as terrorists. Hardline unionist Jim Allister tabled an Assembly motion urging she "consider her position".
Ms Stone, who will step down in June, was at times highly critical of the standard of services offered by the state to those bereaved or injured in the conflict. But she has insisted frustration at lack of political progress was not a factor in her decision to leave.
"I have not reached this decision lightly," she said.
"And it has, unquestionably, been the most difficult decision of my professional life and possibly the most emotionally taxing.
"I am very sorry to be leaving a place that has become my home and leaving people who have become close friends."
Stormont First Minister Peter Robinson and Deputy First Minister Martin McGuinness have paid tribute to Ms Stone's work and said they were sorry to see her go.
"She has been tireless in her efforts to ensure people, families and groups were afforded a quality service, in acknowledging the legacy of the past and in building a better future," the ministers said in a joint statement.
The leaders said they were committed to implementing Ms Stone's recommendations to improve Northern Ireland's Victims and Survivors Service.
"Throughout her time in office, Kathryn offered clear independent advice to Ministers on matters affecting victims and survivors," they added.
"Kathryn brought considerable experience and professionalism to the post. She has represented and worked for all victims to highlight their concerns and improve their lives and we will be sorry to see her leave.
"We thank Kathryn for her work here and wish her every success in her new post."
The outgoing commissioner said it had been an honour to work with victims and survivors.
"Throughout my career, I have taken on jobs and roles through which I can potentially make a difference," she said.
"Given the situation here, this has been the most challenging role of my career. I am therefore grateful for the kind and thoughtful words of the First Minister and Deputy First Minister.
"I have been uniquely privileged to serve individuals, families and groups and would further hope that they, most importantly, feel that I have made a difference: that I have represented them openly, fairly and with passion. It has been my guiding principle not only to give them a voice but to give them a voice that is heard, listened to and acted upon."
She added: "I wish my successor well. I also hope that in Northern Ireland we can continue to embed and strengthen the political process for the benefit of everyone."
A spokeswoman for the commissioner said she had been offered the opportunity to work in "another critically important area of public life" and said an announcement on her new role would be made shortly.
The ministers said the recruitment process to find a new commissioner would start as soon as possible.
Kathryn Stone was born in Derby in 1963 and has a younger brother – she describes him as the "successful one in the family" – who now runs Plantscape, a company specialising in plant display, landscape services and interior/exterior plant displays for special and corporate events.
Her father, a former member of the RAF, was a florist and the family lived above a flower shop. Her parents also ran the corner shop which was "literally open all hours, but only in the morning on Christmas Day".
According to Stone, "lots of people came in from a 'doss house' down the road and I was always fascinated and a bit scared of them. But my Mum was always respectful and kind to everyone. She has been very saddened by recent things said about me."
Her grandfather, to whom she was very close, was a policeman: "I developed a very strong sense of right and wrong from him, although policing in rural Derbyshire was nothing like Northern Ireland".
Her first school was the local High Street Infants, where she hated the free school milk so much – she says it always tasted sour – that she still prefers to have juice, or water on her cereal.
She then attended Belper High School, "a very different school for its time. There were no uniforms, teachers were called by their first names and there were no playgrounds, just common rooms with sofas and carpets. There was an expectation of community participation and demonstration of social responsibility which instilled in me a very strong sense of duty to society and helping those who are disadvantaged."
She went to London to do a degree in sociology and social work, spending many weekends and holidays in children's homes, day centres, old people's homes and secure units: "Anywhere and everywhere with people, always with people, listening to and learning from people."
She graduated in 1985 and followed up with a Masters from Loughborough College. She began a PhD but gave it up after two years when the combination of a full-time job in child-protection and a baby and toddler proved too much.
She is married to Gray, a writer, journalist and trainer. They have three children: Conor (22) a drama student: Maisie (19 and with chronic fatigue syndrome, or ME) a photographer; and Bella (11) "who wants to be an actor, or an architect, or a marine biologist".
Before taking up her post as Victims Commissioner she was chief executive of Voice UK, a national learning disability charity, promoting justice and well being for vulnerable victims.
In 2007, she was awarded an OBE for services to people with learning disabilities: "I thought it was a formal letter from the Inland Revenue so I didn't actually read it until later in the evening." Over the years, she worked very closely with police forces across the UK on a range of issues, including hate crime against disabled people. She was involved in the investigation into the fire that killed the six children of the Philpott family in Derby: "three adults were given long sentences. It was justice for society, but too late for the children".