Serial child killer Robert Black has died in prison in Northern Ireland aged 68.
Northern Ireland Prison Service confirmed an inmate died in non-suspicious circumstances.
Prison sources have said the dead prisoner was Black.
The Scottish-born killer was serving 12 life sentences for the murders of four schoolgirls in the 1980s.
One of his victims was West Yorkshire schoolgirl Sarah Harper.
In 1994, Black was found guilty of three unsolved child murders in the 1980s - those of 11-year-old Susan Maxwell, from the Scottish Borders, five-year-old Caroline Hogg, from Edinburgh, and Sarah, 10, from Morley, near Leeds - as well as a failed abduction bid in Nottingham in 1988.
His reign of terror was ended in 1990 when he was caught red-handed by police with a barely alive six-year-old girl hooded, bound, gagged and stuffed in a sleeping bag in the back of his van in the Scottish village of Stow. He had sexually assaulted her moments earlier.
In 2012, he was found guilty of the 1981 murder of nine-year-old Jennifer Cardy, from Ballinderry, Co Antrim.
He was also suspected of involvement in other killings.
He had long been the prime suspect in the case of missing 13-year-old Genette Tate, who was last seen in a rural lane in Aylesbeare, Devon, in 1978.
No trace of the newspaper delivery girl has ever been found. All that remained at the scene were her bike and scattered papers.
Former Huddersfield detective John Stainthorpe was one of the men who brought Black to justice.
Mr Stainthorpe, West Yorkshire’s longest-serving detective, headed up the team investigating the Sarah Harper case.
A NI Prison Service spokeswoman said: “The Prison Service has confirmed that a 68-year-old prisoner has died at Maghaberry Prison.
“While this is not being treated as suspicious, the Prison Service has informed the PSNI, Coroner, and Prisoner Ombudsman. It would not be appropriate to comment further at this time.”