More than 24 hours after the sensational killing of Assistant Sub-Inspector Harjit Singh, the police were yet to make a significant breakthrough in the case, with investigators scanning CCTV footage to trace the movements of the suspects.Preliminary investigation suggested that two Sikh men suspected of being involved in the killing were seen fleeing on a scooter from the Bhagtanwala grain market around 12.32 am. Investigators were examining CCTV footage from different points to establish their route. Sources said the suspects might have escaped towards the Tarn Taran side, though the police remained tight-lipped about the investigation.Director General of Police (DGP) Gaurav Yadav, who visited Amritsar on Friday, said specialised teams had been constituted to crack the case. He said the investigation was being conducted on a “war footing” and assured that the suspects would be arrested and exemplary punishment would follow.According to the preliminary findings shared by the DGP, the ASI was shot from close range. The bullet hit the area behind his neck, killing him on the spot. A .30-bore cartridge case was recovered from the crime scene.Harjit Singh was shot dead by scooter-borne assailants while on duty near the Bhagtanwala grain market in the intervening night of Thursday and Friday. He was deployed with the Gate Hakima police station and had been performing security duty at the market when the assailants allegedly opened fire at him.Harjit Singh had left for duty around 9.30 pm. The police received information through the emergency response system at 1.05 am that a cop had been shot.The killing has also raised questions over the security arrangements at the grain market. Amandeep Singh Chhina, president of the Galla and Arhtiya Association, Bhagtanwala grain market, said the association had met Police Commissioner Harmanbir Singh Gill last month, seeking additional security to regulate the inflow of crop produce during the peak season.He said the police had deployed six personnel—three during the day and three at night—from September 3. Harjit Singh was posted on the night shift. Around 20 private security guards were also deployed at the market, he added.The killing comes amid a series of attacks on police personnel in the region. Two policemen were earlier shot dead in Dorangla, Gurdaspur, in a case subsequently cracked by the police. ASI Joga Singh of the Amritsar City Police was also shot dead in the Majitha area, while ASI Jaswant Singh was targeted in a separate firing incident in the Rajasansi area. He escaped with a minor head injury.An obscure outfit, Tehreek-Taliban Hindustan (TTH), had claimed responsibility for three earlier attacks, though the police investigations into the incidents are separate.