A second inquest has opened into the death of a 64-year-old man who died in April 2010 following complications from colorectal surgery at University Hospital Limerick.
Michael Daly's family believe he died as a result of a post-operative leak which was not acted on and which subsequently lead to his death.
His family have campaigned for over a decade to reopen the inquest into their father's death.
Coronor John McNamara was told today that the family believe that new evidence to be presented to him will cast doubt on his original findings in 2012 that the man's death was due to natural causes and cardiac failure.
They thanked him for re opening his inquiry, as second inquests are rare.
Mr Daly, a father of six from the Lee estate in Limerick, had colorectal surgery in August 2007 to remove an advanced tumour.
The surgery was performed by general surgeon Dr Raphael Keane, who had frequently performed colorectal and gastric surgery during his career.
Subsequent to this Mr Daly suffered a number of complications with rectal bleeding and discomfort in his pelvis and was admitted to UHL on a number of occasions.
He died in Milford hospice in Limerick on 7 April 2010.
His son Mike Daly, in his deposition to the inquest today, said his family believe that their father suffered a post operative leak following his surgery in 2007 that went unnoticed and that multiple tests over the following two years that highlighted serious issues also went unnoticed and untreated.
He said they were never told that his father had developed sepsis or septicaemia or VRE, a superbug which affects the bowel.
He said they only discovered this on researching thousands of their father's medical records following his death.
He now believes that if appropriate protocols were followed his father would have survived and he would have avoided what he described as horrendous suffering in the two years prior to his death.
The family accept their father had been diagnosed with angina, which had been diagnosed back in 2000.
In his evidence to the inquest Dr Keane said the surgery on Mr Daly was difficult because of the size of the tumour.
Subsequent tests showed no recurrence of his cancer, and eight months after his initial surgery he had further surgery to reverse an ileostomy, which went ahead after he was confident enough it had healed, and tests were negative for any internal leaks.
He did not agree that Mr Daly had large abscesses in his pelvis and that any inflammation of his pelvic area was as a result of the radiotherapy he had to treat his cancer.
Dr Keane added that Mr Daly had a legion of blood culture tests in the months prior to his death and only one, in March 2010, was positive for septicaemia, which was treated with appropriate antibiotics.
He said the presence of the VRE superbug often occurs with rectal and faecal problems, and the treatment of it is to isolate the patient in a high dependency unit away from other patients so that it does not spread, and this was done with Mr Daly.
The inquest is due to continue for five days.
