The police arrested Santhosh, a native of Payimbra near Koothuparambu on Friday, in connection with the 2009 conspiracy to murder RMP leader T.P Chandrasekharan.
Santhosh was the driver of the jeep that was used by the gangsters to transport quotation teams to various places.
The police also took the vehicle into custody. On the direction of the police, the vehicle was produced by its owner.
The SIT probing the 2009 conspiracy is all set to submit the chargesheet at the judicial first class magistrate court in Vadakara, soon. So far, 13 of the 14 accused have been arrested.
Manoj Kumar, alias Kirmani Manoj, figures as the first accused in the chargesheet along with T.K. Rejeesh, another accused in the case.
The CPM leaders accused include Kozhikode district committee member C.H. Ashokan, Onchiyam area committee member K.K. Krishnan, Thalassery local committee member P.P. Ramakrishnan and Kunnummakkara local committee member K.C. Ramachandran.