Jean-Luc Brunel, 75, was discovered in his cell in La Santé prison in southern Paris, the BBC reported, citing French media outlets.
The newspaper cited a French official, who spoke on the condition of anonymity because an investigation had been opened.
Brunel was being held in an investigation into the rape of minors and trafficking of minors for sexual exploitation, according to the AP.
He was a frequent companion of Epstein and was considered a key figure in French authorities’ investigation into alleged sexual exploitation of women and girls by the U.S.
“It makes me angry, because I’ve been fighting for years,” Huisman, a Dutch former model who claimed she was raped by Brunel as a teen, told the AP.
On Tuesday, Britain’s Prince Andrew agreed to settle a case in which Giuffre accused him of sexual abuse when she was 17.
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