In his testimony, Gerry Adams said he had known the allegations against his brother since 1987 and confronted him privately about them. He denied helping to get his brother a job as a youth worker in the 1990s in Catholic west Belfast, Adams' power base.
Aine Adams returned to police to report the crimes again in 2007, the same year that Sinn Fein ended decades of boycotting the British forces of law and order in Northern Ireland. Accepting police authority opened the way for Sinn Fein to enter a power-sharing government for Northern Ireland in fulfillment of the territory's Good Friday peace accord.
Aine Adams waived her legal right to anonymity in December 2009 on a Northern Ireland news program, during which she accused Sinn Fein of seeking to protect the party's image by silencing her.
Liam Adams shortly thereafter fled Belfast, saying he could not receive a fair trial. He was extradited from the Republic of Ireland in 2011.
Sinn Fein long was the public face of the Irish Republican Army, an outlawed group that killed nearly 300 police officers as part of its failed 1970-1997 campaign to force Northern Ireland out of the United Kingdom. In Catholic west Belfast, people seeking punishment of crimes were warned not to tell police and instead report them to Sinn Fein. IRA "punishment" squads typically would shoot the offenders in the arms or legs, or issue death threats requiring them to flee Northern Ireland.
The dominant IRA faction, the Provisionals, stopped conducting such attacks in 2005 when it renounced violence and disarmed. Today Sinn Fein officials sit on a cross-community panel that oversees the Northern Ireland police.
Gerry Adams offered no comment Tuesday on his brother's conviction. By coincidence, at the time of the verdict he was speaking in the Irish parliament in Dublin on the need for other victims of child rape to receive immediate state protection and swift access to justice.
Adams, 64, has led Sinn Fein since 1983 and built it into the largest Irish nationalist party in Northern Ireland. He held the British parliamentary seat for west Belfast until 2011, when he won a seat in Dail Eireann, the parliament of the Republic of Ireland. British and Irish government and security officials say he was a Provisional IRA leader from the early 1970s to 2005, but Adams denies this.