Disgraced former celebrity publicist Max Clifford has died, the UK's Ministry of Justice said.
The 74-year-old was said to be "in a bad way" after collapsing twice at Littlehey Prison in Cambridgeshire, where he was serving an eight-year jail sentence for historic sex offences.
A spokesman for the Ministry of Justice confirmed Clifford died in hospital on December 10.
"As with all deaths in custody, there will be an investigation by the independent Prisons and Probation Ombudsman," the spokesman said.
"Our condolences are with Mr Clifford's family at this difficult time."
His daughter, Louise, 46, told the Mail on Sunday that Clifford first collapsed in his cell on Thursday when he was trying to clean it.
"It was just too much," she said.
She said he collapsed again the next day and was unconscious for several minutes, and after seeing a nurse was transferred to a local hospital where he suffered a cardiac arrest on Friday.
Following this she said he was in a critical care unit and described him as being in a "bad way".
Clifford was jailed for eight years in May 2014 after being convicted of a number of charges under Operation Yewtree, the Met Police investigation set up after the Jimmy Savile scandal.
He was the first person to be convicted as part of the national investigation. During his sentencing, he branded his accusers as "fantasists".
The PR guru, who used his celebrity connections to lure women, was found guilty of a string of indecent assaults - with the sex attacks carried out between 1977 and 1984.
In 2016 he was cleared of indecently assaulting a teenage girl, after being accused of using his power to humiliate the 17-year-old into performing a sex act on him in the 1980s.
Clifford, on the basis of fresh evidence, had been due to appeal against all his convictions early next year, the Mail on Sunday reports.
The former PR mogul, who crafted a reputation for garnering maximum exposure for the fame-hungry wannabes in his charge, had been ill since suffering a heart attack in August.