Chandigarh, June 20 -- Nearly four chemists and jewellers have received extortion calls since June 13 killing of a Sector 11 chemist's cashier, police officials said on Friday. No FIR has been registered as these cases are being looked into and the security around vulnerable business establishments has been beefed up, officials, wishing not to be named, said. Officials believe that some of the callers may be cyber fraudsters while other calls are believed to have originated from gangsters seeking to cash in on the atmosphere of fear created by the sensational murder. The pattern is similar to neighbouring Panchkula where six businessmen, including club owners and liquor contractors, received extortion calls after the June 5 attack on club owner Rattan Lubana. More than a dozen businessmen subsequently approached Panchkula police seeking security, with some being provided personal security officers and enhanced patrolling. In Chandigarh, police have stepped up surveillance around chemist shops, jewellers and hotel owners, besides rounding up suspected aides of gangsters. Addressing mediapersons on Thursday, police officials neither confirmed nor ruled out whether cashier Janki Das was the intended target of gangsters. IG Pushpendra Kumar clarified that Shree Kumar Medical Shop had not received any extortion call. However, investigators also have technical evidence pointing toward a possible targeted attack. CCTV footage shows accused Sunny Mehra, 22, and Aryan Sharma, 19, entering two other shops before Mehra allegedly opened fire inside the medical shop using a Zigana pistol. A police team has already visited Das' family home and native village in Rohru, Himachal Pradesh, to examine all possible motives. Meanwhile, Mehra and Sharma, who sustained bullet injuries during an escape attempt while being brought to Chandigarh from Jammu earlier this week, have been discharged from PGIMER and shifted back to Government Multi-Speciality Hospital, Sector 16. Though both are in judicial custody until July 1, police will interrogate them after doctors declare them medically fit. Arrested by Jammu and Kashmir Police, Amit Kumar alias Sharabi, who has been in seven-day custody, will be brought to Chandigarh for interrogation. In J&K, Amit has a criminal history with one attempt to murder and another NDPS case registered against him. According to Samba police, Amit has been a part of the Khauf gang, which has been active in Jammu and Kashmir for the past four to five years and has links to jailed gangster Rohit Kumar, alias Makhan. Police said Makhan allegedly coordinated extortion rackets in J&K and Punjab while being in prison and maintaining links with Punjab-based gangsters. Besides Amit, Samba police also arrested Ajay Kumar, Manik Sanhotra and Vivek Mehra. Sunny and Aryan are already in Chandigarh Police custody....