Attempts were also being made by CPI(M) to influence the witnesses, the Leader of Opposition in the assembly alleged.
The victim S R Sreejith had died in a private hospital.
His family alleged that he was kicked several times in the stomach and thrashed by the policemen who took him into custody in connection with a case relating to the death of a 55-year-old CPI(M) sympathiser.
Seven police personnel have been suspended in connection with the death of Sreejith so far and a Special Investigation Team (SIT) had been formed to probe the case.
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