DGP (Prisons) Rishiraj Singh has directed IG (Prisons) H Gopakumar to conduct an inquiry and submit a report.
"The IGP will be visiting the jail on March 17 and will be submitting the report by next day," Singh told PTI.
The probe comes in the wake of media reports that jail authorities had lodged Nisham (40) in a cell in the 10th block, which is meant to house prisoners suffering from mental ailments, to exempt him from hard work.
Nisham had been sentenced to life imprisonment by a Thrissur court in January this year besides an additional 24 years and a fine of Rs 80.30 lakh for killing the security guard of his residential complex.
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Nisham, who was in an inebriated state, had assaulted Chandrabose (51) and later rammed his luxury vehicle against him in the early hours of January 29 last year irked over the delay in opening the main gates of his posh residential complex in Thrissur.
The severely injured guard died on February 16 last year.
The case had evoked widespread protests across Kerala.