The police on Sunday arrested a 21-year-old man on the charge of murdering his grandfather near his house at Gandhi Nagar, Velagoundampatti, on Saturday morning. Police said that A. Pusari (75), a paralytic, went out of his house in the wee hours of Saturday to ease himself, and did not return home for a very long time. His wife Ramayee, who went in search of him, found him near the house with injuries on his body. He was rushed to the Namakkal Government Hospital, where he died. Inquiries revealed that Pusari was murdered by his grandson S. Prabakaran (21). The accused was arrested on Sunday and has been lodged at the Salem Central Prison.