Moments later he stopped breathing and couldn't be revived.

Since then, his grief-stricken family has struggled to make sense of their loss.

"Our life now is a daily emotional struggle, us trying to understand why and what has caused the death of our most precious, beautiful son and brother," his father Roy Morena said yesterday.

"One minute he was a fit, young, strong man in the prime of his life and the next we have police knocking on our door to tell us that he had passed away during an arrest."

A post-mortem examination conducted on Mr Morena's body failed to establish a cause of death.

Roy, his wife Sarina and daughter Anna-Lisa hope an inquest starting on Monday will uncover the "whole truth" of that devastating night.

"A lot has happened in the time since Pat was taken away from us," Mr Morena said on Friday, the first time he has spoken publicly since his son's death in Gwyther Avenue on November 8, 2012.

"We hope this inquest finds the truth and that recommendations are made to prevent other families from experiencing our nightmare."

The day after Mr Morena's death, Bulli residents told the Mercury they heard voices which sounded like two men fighting.

"I went out the back to have a look, it sounded like one guy trying to calm the other down - then it went quiet," one witness said.

About half an hour later, he saw "about four ambulances and two police cars" out the front.

"We went out the back and a few neighbours came over at this stage. Looking over the fence into the car park, we saw ambos working on the guy," the witness said.

"The ambos were trying to give him a heart massage, it was quite vigorous."

The day after the incident, Southern Region police commander Mick Fuller said officers had been conducting an investigation around Gwyther Avenue, an area in Bulli "common for drug and property crime", when they stopped the 34-year-old Wollongong man.

"Police were ... targeting specifically drug and property crime. They were in there conducting covert activities and they had cause to stop the deceased," Assistant Commissioner Fuller said.

"Police moved in to have a discussion with the deceased.

"Following that, there was an argument and an arrest followed after that.

"A struggle has ensued and the deceased was handcuffed. He unfortunately stopped breathing a short time later."

Despite attempts by police and paramedics to resuscitate the man, he was pronounced dead on arrival at Wollongong Hospital.

"Other than handcuffs and physical touching, no other tactical options have been used in terms of evidence we've gathered at this stage," Mr Fuller said.

An internal investigation involving the State Crime Command was established, overseen by the NSW Police Professional Standards Command.

The Morena family want closure - answers they hope will bring sense to their grief.

"As a family, we always maintained a close and loving relationship with Pat and relied on each other for emotional support," Mr Morena said.

"Pat was especially close to his mother Sarina. The bond and the love they shared was unconditional. She was his everything and he was hers.

"He will be remembered by us as precious, for his beautiful heart, caring nature and sense of humour, a son and a brother."

The inquest into Mr Morena's death begins in Sutherland Court on Monday.