Iterating that BJP leader and Hemtabad MLA Debendra Nath Roy was "murdered", the saffron party on Tuesday said it had no faith in the post-mortem report, which stated that the "legislator died due to hanging and no injury mark was found on his body".
Calling for a CBI probe into the case, Rahul Sinha, the national secretary of the BJP, said the police and the administration were trying to "project the murder as suicide".
"The state police and the administration want to cover up the matter. The post-mortem report called the murder a suicide. We have no confidence in this report. The state should either hand over the investigation to the CBI or order a judicial probe under the supervision of a sitting judge of the high court," Sinha said.
The Hemtabad MLA's body was found hanging from the ceiling of a verandah outside a shuttered shop near his home in Bindal village of North Dinajpur district on Monday.
Police said a suicide note was found in his shirt's pocket where he blamed two people for his death. Ray's family and the BJP, however, claimed he was "murdered by the TMC", a charge denied by the ruling party in the state.
Ray had won the Hemtabad (reserved) seat on a CPI(M) ticket in 2016 but later joined the BJP. He had, however, not quit his assembly seat.
BJP supporters clashed with police and pelted stones at buses during a 12-hour bandh called by the party in north Bengal on Tuesday over the unnatural death of the BJP leader.
A BJP delegation also met President Ram Nath Kovind on Tuesday and demanded dismissal of the Trinamool Congress government in West Bengal and a CBI probe into Ray's death.