Kochi, Sep 25 : Senior IAS official and Kerala Chief Minister Pinarayi Vijayan's former top aide, M. Sivasankar, was on Thursday questioned by NIA officials in the gold smuggling case for over nine hours, along with prime accused Swapna Suresh, before being allowed to go home. Though he was questioned for the fourth time, it was the first time that Sivasankar was being questioned by the NIA along with Swapna. The gold smuggling case first surfaced when P.S. Sarith, a former employee of the UAE Consulate here, was arrested by the Customs Department on July 5 when he was allegedly facilitating the smuggling of 30 kg gold in a diplomatic baggage from Dubai to Thiruvananthapuram. The case became murkier when the role of Swapna, a former employee of the UAE Consulate and later employed with the IT Department, came to light. Her links with Sivasankar came up later during the investigation and she later revealed that he was her mentor. After his links with Swapna surfaced, Sivasankar was removed by Vijayan from the coveted posts of the CM's Principal Secretary, and also the State IT secretary and subsequently, suspended from service. Meanwhile, a related development, CPI State Secretary Kanam Rajendran expressed surprise that questioning by the central agencies has been going on for a while now and is being centred around the State Secretariat only, and wondered if it is a ploy by the BJP to keep the Left government under a cloud. /IANS