"Three hundred and seventy-nine of the victims are still missing. Most of the people who reappeared claimed that they were arbitrarily detained and transferred to unauthorized places and without the presence of judicial authorities," the organization explained.
Some victims were found beaten and subjected to torture, and cruel, inhuman, and degrading treatment.
"A group of people claim to have been held in coliseums, private homes, and Immediate Attention Commandos (CAI), where they were guarded by individuals in civilian clothes," the Working Group stated.
The detained citizens claimed they suffered physical and psychological aggressions by members of the National Police and the Mobile Anti-Riot Squad (ESMAD). The women also denounced having been victims of sexual violence.
On May 4, two people who had been reported missing during the protests were found murdered in the Cauca riverbed.
"We urge the Attorney General's Office, the Ombudsman's Office, and National Police authorities to investigate these violent incidents and put an end to human rights violations in the country," the organization added.