Nagpur, Nov 30 : A retired Nagpur medical professional's refusal to fund her grandson's studies in the US led to her cold-blooded killing at his hands, police said. The 22-year-old has been arrested for allegedly murdering his grandmother in her room early on Saturday, and sent to police custody. Police said Dr Devkabai Panchbhai 78, who retired from the Government Medical College, was staying with her sick husband on the ground floor of their residence, while their daughter and son-in-law and their son Nitesh on the upper floor. The son-in-law had gone for a morning walk and on his return, found her lying in a pool of blood. While Nitesh remained mum, investigation led to discovery of his involvement, and on questioning, he confessed to the crime, police said. He had gagged her with some cloth and then applied sticking tape to prevent her from raising an alarm before stabbing her with a knife. /IANS