Sinn Fein leader Gerry Adams says the sooner his brother is brought before the courts, the better.
Adams was speaking about his brother Liam who faces 23 charges related to the alleged abuse against his daughter Aine.
In a letter to the Boston Globe today, Adams says the family told the RUC in 1987 when his niece Aine Tyrell, made the allegations against her father.
"When Aine came back to live in Ireland in the 1990s as an adult, I offered to go to the police with her, and I told her I would support her in whatever action she might decide. She told me she wanted Liam to admit what he had done. There commenced a very long and difficult process in which I tried to create the circumstance for him to do precisely what his daughter wanted. He failed to do so.
"Moreover, when Aine decided to go back to the police three years ago, I went and made a statement to the police in support of her.
"While I have acknowledged on a number of occasions publicly that I have regrets about how I dealt with aspects of this issue, my concern throughout has been for my niece. The decisions I took and the approach I adopted were taken on the basis of professional advice.
"This professional advice convinced me that my role was to support the victim, and protect her right to anonymity - while that was her wish. Consequently, I did not tell anyone in Sinn Fein of the allegations.
"All this has been extremely difficult and painful for me and my wider family. My niece Aine deserves justice and has my ongoing support.
"The sooner my brother is brought before the courts the better."