Kolkata, April 3 : The Central Bureau of Investigation (CBI) on Monday issued summons to four customs department officials in connection with the multi-crore cattle smuggling scam in West Bengal. The arrested officials have been under the central agency's scanner for quite some time with regards to their alleged involvement in the case. Although the agency is tight-lipped about the identity and other details of the accused, sources said that they were instrumental in helping kingpin Enamul Haque in getting seized smuggled cattle auctioned officially at much cheaper rates to be smuggled again across the borders. The sources further said that besides customs officials, some top senior officials of the Border Security Force (BSF) were also under the scanner of CBI and Enforcement Directorate (ED) during their respective parallel probes in the scam. Earlier, BSF commandant Satish Kumar, who was posted at the Indo-Bangladesh borders in Murshidabad district of West Bengal, was arrested over his alleged involvement in the crime. It is learnt that during the last couple of days, the CBI sleuths conducted a raid and search operation at the residences of customs officials posted at the Indo- Bangladesh bordering districts of Nadia and Murshidabad. During investigation, they procured a number of incriminating documents on this count. The CBI sleuths also came across some definite clues about the involvement of these four customs officials' involvement in the matter, following which were summoned. /IANS