The body of a 24-year-old booth level worker of BJP was found near a river in Birbhum's Ilambazar area on Tuesday prompting the party to lodge a complaint with the Election Commission.
Bapi Ankur's body was found on the bank of Shal river at Nadas village; the party and his family have alleged that he was strangled to death.
A senior police officer said a case of unnatural death has been lodged. The exact cause of the death will be known after the post-mortem.
Mr Ankur's father Nirmal Ankur said, "I suspect that my son was murdered."
BJP local leader Anirban Ganguly, who met the family, claimed that there were blood stains on his body.
He alleged it could have been the outcome of the Trinamool's "Khela Hobe" (the game is on).
Originally written and uploaded on YouTube by Trinamool leader Debangshu Bhattacharya in January, the jingle "Khela Hobe" has since undergone many variations and seems to have caught the fancy of opposition BJP too.
"The Election Commission must take into cognisance this slogan. We have lodged complaint with the chief electoral officer," he said.
Trinamool's Bolpur MLA and state fisheries minister, Chandranath Sinha, said "BJP is unnecessarily trying to make it a political issue. I demand neutral investigation by police".