: "She said that if she is not posting on social media then it means she is dead.
"So we are just acting based on what she told us to do.
"The Qatari government can easily prove to the international community that she is alive. They have no proof, and that is of concern for us."
GCHR said they received multiple reports that Qatari authorities handed Noof to her family on October 13 and accused the country's authorities or reneging on private assurances that the young woman would be protected during her stay.
Ibrahim said: "What we know for sure is that she is at imminent risk at the moment. She was either killed or detained, there is no doubt about it."
Noof fled Qatar after alleging her family had tried to kill her on three separate occasions.
As part of her return - which would see her stay in a hotel under the watch of security officials - she promised to drop her application for political asylum in the UK.
In early October, Noof tweeted that her father had accessed the hotel she was staying in.
On October 12, she tweeted: "Sheikh Tamim is the only one who can prevent the danger to my life,” a reference to the Emir of Qatar, Sheikh Tamim bin Hamad al-Thani.
She tweeted "still not safe" and later "a bit more OK" the following day following a thumbs up emoji. She has not posted online or been heard from or seen since.
The famous activist fled Qatar in 2019 after claiming years of alleged domestic abuse at the hands of her family.
She stole her dad's phone to request an exit permit as Qatati guardianship laws prevent unmarried women under 25 from travelling alone without the permission of a male guardian.