Prosecutors advised police not to investigate Sinn Fein leader Gerry Adams in 2010 over claims he withheld information about his brother's sex abuse from detectives, it was revealed.
The veteran republican has been accused of waiting almost a decade to tell investigators what he knew about Liam Adams, who was convicted recently of abusing his daughter Aine from when was she aged four until she was nine.
The Police Service of Northern Ireland (PSNI) confirmed it consulted the Public Prosecution Service (PPS) three years ago .
Assistant Chief Constable Drew Harris told a meeting in Belfast: "This matter has been examined to see if we should open an investigation into the case and the advice that we received was not to open an investigation.
"We will re-examine the transcripts (of the recent court case) but all the facts in our knowledge in 2010 have not been moved on materially since the recent trial."
Adams, 58, from Bernagh Drive, Belfast, was found guilty of 10 offences, including rape and gross indecency, against his daughter, Aine Adams.
The abuse was committed over a six-year period between 1977 and 1983, when she was aged between four and nine.
Gerry Adams has claimed there was a lot of disinformation about the case and said the police were aware of it more than 20 years ago.
Today DUP Policing Board member Jonathan Craig said: "It was only nine years later that he came forward with the evidence of that and that was with the background of a planned documentary occurring around what his brother had done."
He added: "It is up to the PPS to justify why they did not prosecute in these circumstances. I have not heard anyone explain why there was a nine-year gap between his knowledge and bringing that forward to the police."
When challenged about when he was first aware of the assaults on his niece and why he did not report them in 1987, the Sinn Fein chief pointed the finger at others.
"The police were aware over 20 years ago and there is a lot of disinformation being flung about in this issue," Mr Adams said.
During the trial Aine Adams gave graphic details of the abuse, which started when she was aged four.
The first rape she remembers took place while her mother was in hospital giving birth to her younger brother Conor in 1977.
The allegations about Liam Adams were first made public when his daughter took part in a television documentary in 2009.
A short time later, Gerry Adams revealed his father Gerry Snr, a veteran IRA man, had physically and sexually abused members of his family.
He was a witness in the first trial which collapsed earlier this year. He told Belfast Crown Court he confronted his brother when they met in Buncrana, Co Donegal, in 1987 and that Liam Adams had denied the abuse.
He then said his brother later confessed while they were out walking together in the rain in Dundalk, Co Louth, in 2000.