Stephen Charters, a former worship leader, was sentenced to five years in prison.
Charters committed a series of rapes and sexual assaults on children as young as four.
An investigation has been launched after his body was discovered in the Hermiston Hall at Edinburgh’s Saughton prison.
The 57-year-old former worship leader attacked a teenage victim in an Edinburgh hotel after she had a fight with her boyfriend and asked Charters for help finding a place to stay.
Instead, he booked a hotel room for her and subjected her to sex acts before rapping her.
He was found guilty last year of nine counts of rape and sexual assault committed against four victims between November 1984 and October 2015.
After his body was discovered, fellow inmates were “kept in their cells,” according to a prison source.
“We didn’t know what was going on,” an insider explained, “but everyone was in their cells after his body was discovered.”
“We knew it was something serious, but no one knew what.”
Then we discovered Charters had died. He only arrived last week.
“There are various stories floating around, but I’m not sure what happened.”
Charters had previously served a five-year prison sentence in 2016 for multiple sexual crimes against children.
Lady Carmichael informed him that his actions had caused “serious and enduring harm.”
“You pose a significant risk of further sexual offending,” she stated.