Rothna Begum, a senior women's rights researcher at HRW, voiced alarm.
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"The case against the witnesses and the smear campaign against them and the rape survivor send a chilling message to survivors of sexual violence and witnesses that they can go to prison if they report sexual violence," Begum said.
It is not the first time those denouncing violence against women in Egypt have found themselves targeted.
Earlier this year, teenager Menna Abdel-Aziz, her face battered and bruised, posted a video on social media in which she said she had been gang-raped.
The authorities' response was swift: they arrested the alleged attackers, along with the 17-year-old girl, charging them all with "promoting debauchery".
Even female social media influencers have been in the authorities' sights.
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In July, five were sentenced to jail time on charges of violating public morals over content posted to video-sharing app TikTok.
Crushing #MeToo
In the Fairmont case, lawyers have fallen silent.
And Egypt's National Council for Women, which had encouraged witnesses to come forward, has instead been accused of throwing them to the lions.
The head of the council did not respond to an AFP request for comment.
The administrator of Assault Police, an Instagram account advocating justice for rape survivors that had reported the case, suspended the account for several weeks after receiving threats, HRW said.
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