[2][3] She is married to Social Democratic and Labour Party (SDLP) councillor and former North Antrim MLA, Declan O'Loan; they have five sons.

[5] Following the long gap after Stanley Burnton was forced to quit,[clarification needed] Baroness O'Loan was made the new head of a long-running series of inquiries into the murder of the ex-private investigator and the subsequent police cover up.

Her report, published in December 2001, found that the Royal Ulster Constabulary had prior knowledge of some form of attack planned for that area and it questioned the leadership of Northern Ireland's then Chief Constable, Sir Ronnie Flanagan.

"[7] O'Loan attracted both praise and criticism for her robust activity in investigating alleged abuses by officers in the Police Service of Northern Ireland (PSNI).

[9] A UK House of Commons Committee reported on the Police Ombudsman in 2005 and praised O'Loan, recommending that she be given wider powers.

In December 2006, an independent survey by the Northern Ireland Statistics and Research Agency found that Protestants and Catholics are equally supportive of the Police Ombudsman.

[10] On 26 June 2007 former RCMP Assistant Commissioner Al Hutchinson was announced as the successor to O'Loan as Police Ombudsman, and he took up the office on 5 November 2007.

Her marriage to a nationalist Social Democratic and Labour Party (SDLP) councillor has, in the past, caused Paisley to question her ability to remain independent.

[15] In August 2008 O'Loan while being interviewed on BBC Radio 4's Woman's Hour caused controversy by reportedly claiming that Protestants in Northern Ireland were brought up not to trust Catholics.

[16] In 2003, the Annual Conference of the National Association for Civilian Oversight of Law Enforcement (a US organisation) presented O'Loan with an award for her contribution to police accountability.

On 3 July 2008, Dame Nuala was awarded an honorary Doctor of Laws (LLD) by the University of Ulster in recognition of her work as Police Ombudsman and for her contribution to the social development of Northern Ireland.

Several crimes committed by informants working for Special Branch were investigated, including the killings of: She was appointed Dame Commander of the Order of the British Empire (DBE) on 29 December 2007 in the 2008 New Year Honours.

[24] On 11 September 2009, she was created a life peer as Baroness O'Loan, of Kirkinriola in the County of Antrim,[25] and she was introduced in the House of Lords on 27 October 2009,[26] where she sits on the crossbenches.