A special CBI court held five policemen guilty in connection with the custodial death of a man in 2005.
The prosecution case was that Udayakumar, 26, who was taken into custody for questioning in a theft case, died in custody after being tortured by police.
Two policemen, who took Udayakumar into custody, were found guilty of murder while three others were found guilty of conspiracy and destroying evidence.
The court would pronounce the sentence today.
A total of six policemen were accused in the case and one died during the course of trial.
The case triggered widespread protests across the state as it was alleged that police had used third degree methods on Udayakumar.
The CBI took over the investigation following a high court order on a plea filed by Udayakumar's mother Prabhavathi.
"No mother should suffer such a trauma like this," Prabhavathi said on hearing the verdict that came after 13 years.
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