The couple moved to London, where in 1969 a woman was abducted and held to ransom in Hertfordshire – mistaken for Murdoch-Mann.
Muriel McKay was killed by her kidnappers and there have been renewed efforts to find her body in recent years.
The then-Murdochs divorced in 1999 in one of the most expensive separations in history – Murdoch-Mann received a $1.7bn (£1bn) settlement.
Murdoch married his third wife, Wendi Deng, 17 days later, Australian media report.
In an exclusive interview after her separation, Murdoch-Mann told Australian Women’s Weekly, external “I think there’s going to be a lot of heartbreak and hardship” over the succession for Murdoch’s media empire.
“There’s been such a lot of pressure that they needn’t have had at their age,” she added.
This battle inspired the television series Succession, and played out in courts in real life. It concluded with Murdoch’s eldest son Lachlan set to control the news group as of late last year.
His mother also remarried, first to financier William Mann who died in 2017.
Murdoch-Mann later wed her third husband, Ashton dePeyster, who survives her along with 10 grandchildren and one great-grandchild.
The philanthropist served on the boards of several children’s hospitals including in Los Angeles and Haiti.
In 1998, she was made a Dame of the Order of St Gregory by Pope John Paul II.