Liam Adams, the paedophile brother of former Sinn Fein leader Gerry Adams, has died.
Adams had been receiving care for terminal cancer at a Belfast hospice after being moved from Maghaberry Prison.
The 63-year-old was found guilty in 2013 of raping and abusing his daughter, Aine Dahlstrom, and was jailed for 16 years.
He was moved to the medical facility earlier this year for end-of-life care.
The Northern Ireland Prison Service confirmed the death of an inmate from Maghaberry.
In a statement, it said: "The prisoner died on Monday morning, 25 February. His next of kin have been informed.
"As with standard procedure, the PSNI and Prisoner Ombudsman have been informed."
Ronnie Armour, head of the Northern Ireland Prison Service, said: "I would like to extend my sympathy to the family of the prisoner.
"My thoughts are with them at this difficult time."
Adams began to abuse Ms Dalhstrom, who waived her right to anonymity, when she was just four years old and continued over a six-year period during the 1970s and 1980s.
Adams, a former youth worker, was convicted of 10 offences - three counts of rape, four of indecent assault and three of gross indecency.
In 2015, Adams lost an appeal at the High Court against his conviction and sentencing.
Gerry Adams, a Louth TD, gave evidence at his brother's first trial - which collapsed in April 2013 for legal reasons.
During the 2013 trial, Mr Adams told the court that in 2000, during a walk in the rain in Dundalk, his brother had admitted sexually abusing his daughter, Ms Dalhstrom.
Mr Adams made his first report to police about the allegations in 2007 shortly after his party voted to accept the PSNI, but did not tell officers about the confession until 2009, when he made a second statement.
Mr Adams was criticised for not informing police about the confession at an earlier date.
In 2015, the Northern Ireland Police Ombudsman found that police were not politically motivated when they said Gerry Adams should not be prosecuted for allegedly withholding information about his paedophile brother.
The police watchdog said there was no evidence of misconduct, or that officers had been influenced by the former Sinn Fein president's status.
Ms Dahlstrom first took the matter to police in the mid-1980s. This was in the midst of the Northern Ireland Troubles and a time when many people in republican communities distrusted and refused to co-operate with the security forces.
She did not pursue the matter at that stage, claiming that detectives were more interested to hear information about her famous uncle than about the allegations she was levelling against her father.
It would be another 20 years before she went to police again, after finding out that her father was working in a west Belfast youth club that her children attended.
Adams subsequently went on the run to the Irish Republic, triggering a long extradition battle.