A report ordered by India's Human Rights Commission says that police in the states of Tamil Nadu and Karnataka have committed serious abuses.
Veerappan died in a hail of bullets
The report deals with the police treatment of villagers during the search for the outlaw Veerappan, who was shot dead in October 2004.
According to leaked details from the report, there is evidence that police killed, raped and tortured villagers.
The police in the two states have always denied wrongdoing.
The report was compiled before Veerappan's death but kept confidential. Details have only now been obtained by the media.
Veerappan was India's most notorious fugitive and for years foiled efforts by the Tamil Nadu and Karnataka police to capture him.
'Shot in the mouth'
The detailed report ordered by the National Human Rights Commission includes many testimonies from villagers which it deems to be "acceptable".
It includes cases of electric shock torture, sexual assault and detainees having their bones broken. It cites one case in which a man was left permanently disabled.
This woman says she was wrongfully imprisoned for eight years
In another, it says a woman died "due to the atrocities by unidentified" members of Tamil Nadu's Special Task Force of the police.
The report also gives the names of more than 30 people it says were killed in what it describes as "suspicious encounters" with the police.
In one case it says a man was shot in the mouth "from contact range".
The report also says many people were wrongfully imprisoned.
Victims of police wrongdoing, it says, should receive compensation.
The report says the human rights commission did not receive enough satisfactory evidence to be able to identify any of the police involved in any of the misdeeds.
The National Human Rights Commission is a body established by law. Its members are appointed by the president after consultation with the prime minister and other leading politicians.
Correspondents say it is expected to give its official reaction to the report later this year.
The governments of Tamil Nadu and Karnataka state have stood by their police forces while other non-statutory human rights groups have accused them of abuses.
The Karnataka government has accused non-governmental organisations in the state of torturing villagers to make false accusations against its police force.