The murder had rattled the CPI-M ranks and caused a huge dent in the image of the party.
Chandrasekheran, who was ousted in 2008 by the CPI-M after he became the proverbial thorn in the side of the party in Kozhikode district, had then founded another political party, the Revolutionary Marxist Party.
As the 51-year-old was returning home near Onchiyam in Kozhikode district May 4, 2012, he was attacked by armed assailants and hacked to death.
Twenty of those accused in the murder were let off Wednesday by special court judge S. Narayana Pisharady, for want of evidence.
CPI-M state secretary Pinarayi Vijayan expressed happiness over the judgment, but state Congress president Ramesh Chennithala hoped that the state government would file an appeal.
K.K. Rema, wife of the slain leader, said that in the minds of the people, those let off are not innocent. As many as 53 witnesses in the case turned hostile, fearing a backlash by the CPI-M.
State Home Minister Thiruvanchoor Radhakrishnan, however, reserved his comments and said that he had not yet seen the verdict.
Among those arrested for this murder were state, district and local leaders of the CPI-M, including the husband of a party legislator.
Among those let off Wednesday were a senior district-level party leader, K. Rajan, from Kannur district of Kerala.
--IANS (Posted on 11-09-2013)