Northern Ireland's First Minister Peter Robinson comes under increasing pressure over allegations about his wife's financial affairs contained in a programme by BBC current affairs programme Spotlight.
BBC News looks at the people at the centre of the investigation.
THE ADVISOR - SELWYN BLACK
Allegations made by Iris Robinson's former political adviser Selwyn Black are at the heart of the story.
Mrs Robinson told adviser Selwyn Black about wanting to help Mr McCambley
Dr Black is a lecturer specialising in trauma counselling.
As part of his work as a counselling lecturer at the University of Ulster, he researched how medical staff coped with helping victims traumatised by the 1998 Omagh bomb.
He also assessed the experiences of doctors caught up in the Bosnian civil war, developing a framework for measuring intensity of trauma.
Before beginning his job as political adviser for Iris Robinson in January 2008, he served as a Methodist minister in Dublin and spent 10 years as a military chaplain with the Royal Air Force.
Dr Black helped Mrs Robinson in her role on Stormont's health committee.
Mrs Robinson sent more than 150 text messages to Dr Black, which traced the development of her relationship with Kirk McCambley.
He resigned in December 2009, the same month that Mrs Robinson announced she was stepping down from political life.
Mr Black told Spotlight he had felt angry he had been "drawn into that situation" but he now felt sorry for her.
THE LOVER - KIRK MCCAMBLEY
Kirk McCambley's father Billy, an east Belfast butcher, was a close friend of Iris Robinson.
Iris Robinson obtained £50,000 for Kirk McCambley with whom she was having a sexual relationship
Before his death in 2008, Mrs Robinson promised to look after Kirk, his only son.
Iris Robinson's maternal instincts soon began to be replaced by more intense feelings and by mid-summer, Mrs Robinson, then aged 59, had begun a sexual relationship with Kirk, then 19.
Mrs Robinson found a business opportunity for the teenager - a new café alongside a 200-year-old lock keepers' cottage on the banks of the River Lagan.
This landmark project was being overseen by Castlereagh Borough Council, and building work was almost finished in June 2008 when the council advertised for a suitable tenant to run the cafe.
With his limited business experience, Mr McCambley needed start-up capital.
Spotlight revealed Mrs Robinson sought and received a total of £50,000 from two property developers.
At her behest, two £25,000 cheques were made out in Mr McCambley's name.
Mr McCambley told Spotlight that Mrs Robinson instructed him to give her a cut - £5,000 in cash.
In July 2008, six weeks after Castlereagh Borough Council advertised for expressions of interest - Kirk McCambley was the sole applicant to meet the criteria.
However, their relationship ended in autumn 2008 and Mrs Robinson wanted the money back.
Mrs Robinson and Mr McCambley saw each other for the last time at a meeting organised by Selwyn Black.
Mr McCambley sold his half-share in the café and paid the property developers £20,000 each, which meant he still had £5,000 of the original money.
In total, £10,000 was still outstanding from the original sum - it is not yet known if Iris Robinson paid all or any of it back herself.
THE DONORS - FRED FRASER AND KEN CAMPBELL
Kirk McCambley's start-up capital was obtained by Iris Robinson from two property developers - Fred Fraser and Ken Campbell.
Fred Fraser died in August 2008, just weeks after he had written out a cheque for £25,000.
For many years, Mr Fraser was the biggest name in house building in Northern Ireland - particularly in Castlereagh.
Ken Campbell runs a County Down-based property development business.
In 2004, he joined the board of Belfast's Titanic Quarter, a multi-million pound development aimed at regenerating a run-down area of east Belfast.
THE POWER COUPLE - PETER AND IRIS ROBINSON
Northern Ireland's First Minister Peter Robinson revealed on Wednesday his wife Iris had tried to take her own life in March 2009 after admitting her affair with Kirk McCambley.
Following his revelations, the BBC's Spotlight programme confirmed it had been investigating matters involving Iris Robinson for some time.
Mrs Robinson broke the law by not declaring her financial interest in a business deal
Iris Robinson announced in December she was stepping down from politics due to ill health. The couple were married in 1970 and have three grown-up children.
Mrs Robinson obtained £50,000 from Mr Fraser and Mr Campbell to help Kirk McCambley launch his café. She later asked him for £5,000 for herself.
Spotlight reported that Mr Robinson became aware of the money she had obtained from the developers.
The programme said that while he pressed his wife to return the money, he failed to tell the proper authorities about the transaction, despite being obliged to act in the public interest by the ministerial code.
The programme said that while Mrs Robinson was asking Mr Campbell for the money, she also lobbied on his behalf for one of his building projects in her parliamentary constituency.
The laws covering local government state that once Mrs Robinson had a financial interest in the business, she was obliged to declare it at any meeting she attended where it was being considered.
She failed to do so.
Spotlight reported that she also broke a cluster of other rules in the Code of Conduct for councillors - as many as five elements of the code.
As an MP, she was also legally obliged to declare the £50,000 she obtained from the developers in the register of members' interest at both Stormont, where she served as an MLA, and Westminster.
She failed to do so.
When Peter Robinson found out about his wife's financial dealings, he insisted that the money should be returned.
However he did not tell the proper authorities what he knew about the transaction despite being obliged by the ministerial code to act in the public interest at all times.
On Thursday, Mr Robinson's solicitors said he was thoroughly satisfied that he has at all times acted properly and fulfilled all requirements, and would robustly challenge any allegation to the contrary.
They said that Iris Robinson was too unwell to respond.