Terence McDaid was killed in 1988 in a case of mistaken identity by a gang who had set out to kill his brother David.
The gunmen burst into his north Belfast home and shot him dead.
His daughters Patricia and Tracey were just six and eight years old at the time.
"I just remember my daddy lying there," Tracey told UTV Live Tonight.
"When we came down the stairs we were told not to look in the room, but I was eight at the time and of course I looked and seen him lying there.
"That picture will never leave me."
"It was the beginning of a different life," Patricia said.
"It wasn't the life my mummy and daddy would have provided for me if they'd both still been here.
"Everything changed that night."
All these years later it is still so difficult and it's because there is no justice.
It was known that an army agent, Brian Nelson, had supplied the UDA with Terence's address, but new information in the recently published Pat Finucane review has also unveiled the integral role he played in the murder.
"This report provides fresh evidence and detail in relation to the very direct role the state agent Brian Nelson played in the targeting of Declan McDaid and the murder of Terence McDaid," the family's lawyer Padraig O'Muirigh explained.
"We now know that he had a very direct role in targeting Mr McDaid, he provided intelligence information, he carried out a visit of the area, we know now that he met with his handlers the day after the murder and provided information in relation to his direct role.
He continued: "It's very clear that the information was also passed to Special Branch, and we now have a date that almost a month before, Mr McDaid was murdered, the RUC were well aware that Declan McDaid, his brother, was being targeted and they took no action."
We also know from documentation disclosed in the report, that Special Branch were well aware of who was involved in the murder and again they did not investigate this.
Padraig O'Muirigh, family lawyer
The authorities have previously paid compensation privately to Mr McDaid's widow Maura and their eldest daughter, Tracey.
Patricia did not receive anything as she was deemed to be too young to have suffered any lasting psychological damage.
With previously classified intelligence documents now in the public domain, she will be taking legal action against the Ministry of Defence and the police.
Tracey said that now the review has confirmed the collusion, she wants questions to be answered and for those responsible brought before the courts.
"We want justice and for people to admit that, yes, there was collusion in my daddy's case," she said.
"They came into the house that night, murdered my daddy and walked away, and left devastation behind them.
"They are walking the streets. They are probably not even affected by it."
Patricia added: "Closure would mean knowing the truth, and being able to move on with life."