According to a statement, Ramachandran had personal animosity with Chandrasekharan, a CPI(M) rebel who floated a parallel left outfit called Revolutionary Marxist Party (RMP) at Onchiyam in Kozhikode district.
The CPI(M) decision drew immediate flak from RMP leaders who dubbed it as a "ploy" to wash the party's hand offs the case, the conspiracy angle of which is being probed by CBI.
Chandrasekharan was brutally hacked to death on May 4, 2012. A special court in February this year sentenced 11 persons, three of them local CPI(M) functionaries, to life imprisonment in connection with the case.
The Chandrasekharan murder case is considered one of the issues to prominently figure in the Lok Sabha polls.