Former Northern Ireland Ombudsman Tom Frawley has been appointed as an independent member of Belfast City Council's investigation into its controversial storage of bonfire material.
The investigation is headed by council chief executive Suzanne Wylie.
Mr Frawley will assess the evidence as the probe progresses.
Council sources have indicated to the Belfast Telegraph that internal whistleblowers who would not be confident making disclosures to City Hall staff would be free to approach him.
The investigation is into the council's gathering and storing of more than 3,000 pallets for two controversial loyalist bonfires and the subsequent theft of the material.
All political parties in City Hall voted for the probe, although the DUP insisted that council officers had done nothing wrong. Sinn Fein was furious when it discovered that the council was storing pallets for bonfires in Chobham Street in east Belfast and near to the Holiday Inn in Sandy Row.
The party's group leader Jim McVeigh said that most councillors had been "kept in the dark" about the decision, which had "seriously damaged the reputation of this council across this city in the minds of many, many people".
He accused the council of "facilitating illegal bonfires".
The bonfire builders were later aghast when the pallets they had handed over for safe keeping were stolen from council premises on Gransha Road.
The investigation was expected to be completed by next month, but City Hall sources now believe it will likely take until October.
It will seek access to all emails and communications between council officers internally and with outside agencies - and who that information was shared with. The probe will examine who made the ultimate decisions regarding storing the material and with whom they consulted.
Alliance group leader Michael Long said that the investigation would also examine the wider bonfire issue in Belfast.
"It is important to review how the bonfire management scheme operated this year as well as the council's decision to store pallets," he said.
"We are keen to get the investigation to report back as soon as possible so that the same mistakes are not repeated."
Mr Frawley last year retired as Northern Ireland Ombudsman, a position he had held for 16 years.
His career started in 1971 when he joined the NHS. In 1985 following the implementation of the Griffiths report he was appointed the Western Health and Social Services Board's general manager.
A series of fellowships led to health care study visits in Australia, New Zealand, the USA and Zimbabwe, and in 2000 he took on the role of Northern Ireland Ombudsman.