Madurai: K Saravanan, 40, had seen the trick in a Tamil film — murderers sprinkling sugar to invite ants and help erase footprints around a dead body. On Sunday, he along with his lover employed it to cover their tracks after murdering a 70-year-old woman for her gold, but little did he realise that CCTV cameras were watching.Saravanan and M Chanmundeswari, 33, were arrested on Monday for murdering Poochiyammal of Soorakudi in Sivaganga district. Police said the the elderly woman had left home on Saturday evening to visit her relatives. As she failed to return, her husband, Madhavan, filed a missing complaint with S V Mangalam police. Her body was found the next morning near a canal close to a govt school in M Soorakudi near Singampunari. Police said the body was covered in sugar.“Many accused sprinkle sugar believing it will accelerate decomposition, attract insects, suppress odour or help burn a body. Most of these beliefs are scientifically flawed. In this case, ants could have altered footprint impressions, but they could not erase the cameras that had recorded Poochiyammal’s final movements,” a forensic scientist said. Investigators use an electrostatic dust-print lifter to transfer minute dust impressions onto film before photographing and comparing tread patterns, size and wear marks. The sugar was meant to disturb dust footprints around the corpse.Police said after Chamundeswari’s husband died a year ago, she entered into a relationship with Saravanan in Chennai. The couple had debts and targeted Poochiyammal after noticing that she regularly wore gold ornaments. Chamundeswari allegedly invited her home. The pair smothered her with a blanket, removed the jewellery, sprinkled sugar on the body and placed it inside a sack. They dumped it in the canal that night.However, CCTV footage, a sniffer dog, forensic evidence and information from villagers helped police identify and arrest the pair within five hours of finding the body. Police recovered 10.5 sovereigns of Poochiyammal’s jewellery from Chamundeeswari’s car during questioning.Police said the couple discarded her cellphone, slippers and other materials at separate locations to divert the investigation. Saravanan reportedly admitted using sugar after watching the method in a film. Saravanan and Chamundeswari were remanded in judicial custody and further investigation is under way.