Six days after Punjab Police constable Karandeep Singh was allegedly caught with 15 kg heroin near Tarn Taran, the Narcotics Control Bureau (NCB) has arrested three more persons, including a former Aam Aadmi Party (AAP) sarpanch, in connection with an alleged cross-border smuggling network.Those arrested have been identified as Lakhwinder Singh, former AAP sarpanch of Rajoke village in Tarn Taran; Babbu alias Vishal of Bhuse village; and Sukhmanpreet Kaur, a Delhi resident who allegedly collected drug consignments on behalf of a narcotics accused.A senior NCB official confirmed the arrests and said further investigation is underway.Investigations so far have revealed that Karandeep Singh, who was attached to the Punjab Police’s anti-drone unit, allegedly worked for Lakhwinder Singh, who is suspected to have been in contact with Pakistan-based smugglers. The network allegedly used drones to smuggle narcotics and weapons across the international border.Karandeep, who is himself a drug addict, was arrested by NCB on October 14.Talking to The Tribune, an NCB official said Lakhwinder Singh had allegedly facilitated around 15 consignments. He would obtain Karandeep Singh’s duty schedule to facilitate smuggling, sources said.The case has raised concerns as the constable was serving in a unit tasked with intercepting drug consignments dropped by drones from across the border. NCB had arrested him with 15 kg heroin from Naushera Dhalla village in Tarn Taran.Investigators are also examining the constable’s financial transactions, assets and property holdings to establish whether he accumulated wealth through the alleged smuggling network.Sukhmanpreet Kaur, who hails from Delhi, had reportedly been studying in Amritsar. She allegedly collected consignments on behalf of a drug peddler who is currently lodged in a Haryana jail. She claimed to have cleared the preliminary examination for the Punjab Civil Services (PCS), while sources said she is the daughter of an Assistant Sub-Inspector (ASI) posted with the Delhi Police.NCB is investigating the accused’s alleged links with Pakistan-based smugglers and the extent of the network’s operations. Further details are awaited.