New Delhi, Sep 22 : National Investigation Agency (NIA) has filed charge sheet against 13 persons in the Villianur (Puducherry) bomb blast case, involving the assassination of a political functionary in the attack. On March 26, six motorcycle-borne assailants had hurled country made bombs at Senthul Kumaran in front of a bakery located at Villianur in the Puducherry. The accused then attacked the victim with machetes, killing him on the spot. The local Police had initially registered a case, which was handed over to the NIA. The key conspirator in the case, Nithyanandam, was later arrested, along with his associates, identified as Vignesh, Siva Sankar, Raja, Pradap, Karthikeyan, Vengatesh, Rajamani, Ezhumalai, Kathirvel, Ramachandiran, Lakshmanan, Dhilipan and Ramanathan. All of them, except Ramanathan, have been chargesheeted by the NIA under various sections of IPC, Arms Act, Explosive Substances Act and UA(P) Act. NIA said that the conspiracy to attack Senthil Kumaran was masterminded by Nithiyanantham with the aim to strike terror among the local people in Villianur and surrounding areas. The agency said that in furtherance of the conspiracy, Nithiyanantham had formed a terrorist gang to fabricate countrymade explosives and had also organised the machetes to commit the brutal attack. "As part of the conspiracy, Nithiyanantham had sent Kathirvel to conduct surveillance on Senthil Kumaran in Villianur. After Senthil's presence in the area was confirmed, the main accused sent the six assailants, Vignesh, Siva Sankar, Raja, Pradeep, Karthikeyan and Vengatesh, on three motorcycles to carry out the assassination," the NIA said. NIA said that after the attack, the accused had hidden the vehicles and blood stained machetes used in the assassination, along with their blood stained clothes. NIA said that recovery of these items was made during investigations, on the basis of their disclosures. /IANS