that Sutcliffe — who murdered 13 women and attempted to kill another seven — "frightened to death" Dr Sasieni, 54.
The former lag got to know Sutcliffe at HMP Armley in Leeds as he awaited his trial in 1981.
He told him: "She was saying things that upset me, so I thought, ‘I’ll upset you’".
Sutcliffe, then 34, bragged "that she died the next day, after going off work for a two-week holiday", the source said.
Sutcliffe, 71, is now in poor health at maximum security HMP Frankland in Durham.
He was dubbed the Yorkshire Ripper during his murder spree in the 1970s across the North.
One of the survivors of his attacks told The Sun last month that she hopes to see him in court before he dies.
Tracy Browne – a 14-year-old schoolgirl when he bludgeoned her with a hammer — hopes a cold case probe into unsolved Ripper attacks will see the fiend back in the dock.
"I absolutely want my day in court if he’s tried again", she said.
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