A group of assailants on Friday hacked to death a medical shop owner belonging to Tiruvermbur. The assailants waylaid Thiyaga Panchabakesan (42) when he was returning to Tiruverumbur from Thirukattupalli in Thanjavur district after closing his medical shop on Friday night. They attacked his brother Kanagaraj, who came to his rescue. They then fled in a car, a source said. While Panchabakesan died on the spot, Kanagaraj has been admitted to a hospital at Thirukattupalli. The reason for the murder was not known.