Prosecutors in Egypt have shelved a case that fuelled Egypt's #MeToo movement, saying there is "insufficient evidence".
A woman alleged in a social media post last year that she was drugged and gang raped at the five-star Fairmont Nile City Hotel in Cairo in 2014.
Following a nine-month investigation the four suspects in the case have now been released, prosecutors said.
But they added that the case could be reopened if new evidence came to light.
In a statement, prosecutors said they had pursued the suspects last year by enforcing travel bans and issuing international arrest warrants for three of the men from Lebanon.
But, they added, "there is insufficient evidence against the defendants to proceed with a criminal case. The release of those temporarily detained has been ordered".
They said they had interviewed 39 witnesses, and that "contradictions appeared in the testimonies of witnesses about key facts of the incident".
Prosecutors also questioned police and forensic doctors, they said, as well as the alleged victim.
Assault Police, the campaign account that first reported the allegations last year, posted about the case being dropped with the hashtag "#justiceforthefairmontsurvivor".
When it was first publicised last year, the case led to people across Egypt sharing their experiences online of sexual harassment and assault.
Last year, the Egyptian parliament approved a law intended to encourage victims of crimes to report them by giving them the automatic right to anonymity.
Research suggests that abuse is widespread in Egypt, but that women are afraid that if they file complaints they themselves could be blamed.