The gang members had followed Ilanchezian in a car and knocked him down from his two-wheeler when he was returning after dropping his children, police said. They had then hacked him to death before fleeing the spot, they added.
Ilanchezhian was allegedly involved in some murder cases, including that of the recent murder of a 16-year old son of a former leader of ''Puthia Tamizhagam'', a political party that advocates the rights of those belonging to the schedule caste communities, police said.
They added one of the accused, Kasiviswanathan, had already surrendered. Kasiviswanathan, who allegedly led the gang that killed Ilanchezhian, had enmity with the victim for the past three years, they said.
He had earlier tried to plant some bombs in Ilanchezhian's farm at Avaniapuram near here, they added, but Kasiviswanathan himself got badly injured as the bombs went off accidentally.
Ilanchezhian had also been arrested along with Kasiviswanathan in connection with the explosion, as it had taken place in his farm, but was then released, police said. Police said they were confident of nabbing the other culprits involved in the murder.