The eight were arrested on July 2 for allegedly torching a sand-laden truck, which was involved in a road accident, causing the death of a person.
They also allegedly attacked policemen in connection with the incident at a village in Rajanna Sircilla district.
Some political parties and outfits had alleged the accused, residents of Nerella, were "tortured" while in police custody and subjected to "third degree methods".
Addressing a press conference after visiting the Karimnagar District Prison where the accused are lodged, Kumar said "A judicial inquiry should be ordered to find out veracity of allegations that they were illegally confined in the police station and subjected to third degree methods".
The Congress will raise the issue in Parliament, she said.
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