Half of India's police believe Muslims 'naturally' commit crimes
The report surveyed around 12,000 police personnel in 21 Indian states.
It also found that one in three police staff endorse killings and mob justice in cases of outrage over cow slaughter.
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In addition, around 40% justified mob violence for those accused of rape, kidnapping, or even road accidents involving negligent drivers, and nearly one in five said it was better for dangerous criminals to be killed than to have a trial.
"Some of the findings were very surprising," Manjesh Rana, one of researchers on the study, told Al Jazeera. "We believe that this could be the perception of the people but not the perception of the police."
"We can't really establish that the prejudices they have, whether it's affecting their work or not but there are always these chances," he added.
The findings come amid an increasingly fraught atmosphere in India between the majority Hindus and Muslims. Rights groups and the United Nations have expressed concern over an increase in harassment and violence against India’s Muslim minority.
Dozens of Muslims and low-caste Hindus have been killed by Hindu right-wing vigilante groups in recent years over instances of cow slaughter and petty theft, often forced to chant “Jai Shree Ram” (Victory to Lord Ram) while being brutally beaten on video.
Critics of current Indian Prime Minister Narendra Modi say that his Hindu Nationalist Party has emboldened these groups since they swept to power in 2014.