More than 150 convicts have died as a result of serious injury or torture in El Salvador since police began locking up thousands of gangsters in mega jails in March.
Earlier this year, the Central American country's President Nayib Bukele announced the controversial crackdown against the ruthless MS-13 and 18 gangs, which were making the streets a warzone.
None of those who died had been convicted of a crime they were accused of at the time of their arrest. There were four women among the victims and the rest were men.
The deaths were the result of torture, and systematic and serious injuries, a report said. Nearly half of the victims suffered violent deaths.
Some of the deaths showed signs they resulted from deliberate denial of medical assistance, medicine and food, including some deaths resulting from malnutrition.
The deaths revealed punitive policies carried out by guards and prison officials. The report stated that such actions would have required authorisation and backing by the highest-level security officials.
The government has not provided an official count of deaths among the incarcerated.
The special powers were approved by El Salvador's Legislative Assembly in March 2022, following a surge in gang violence. It suspended some fundamental rights, such as informing someone of their rights at the time of arrest and the reason for their, as well as having access to a lawyer.
Cristosal said it compiled the information through fieldwork, including at common graves, and collecting documents from medical examiners.
Investigators also interviewed victims' families and neighbors, as well as others who were jailed and later released.
The organisation called on the administration of President Nayib Bukele to answer about the conditions people were held under, respect due process, free the innocent, answer for those who have died, provide all available information to victims' families, and end the measures implemented under the special powers.
Officially, the government has arrested more than 68,000 people under the special powers since March 2022.
More than 5,000 people have been freed because they could not convince a judge they were tied to criminal structures, according to authorities.
Other human rights groups and foreign governments have condemned the government's actions and called for a lifting of what were supposed to be temporary measures.
Bukele, however, maintains high levels of approval within El Salvador for his actions against the gangs.
