A worker from Rashtriya Swayamsevak Sangh (RSS) was shot and killed in Mambaram in the district on Monday morning, police said.
Police said the 27-year-old Sanjith was beaten to death in front of his wife around 9 a.m. as he was driving her to her workplace.
The role of activists from the Social Democratic Party of India (SDPI), the political branch of the Islamist group Popular Front of India (PFI), is suspected in the incident, they said.
An investigation was launched to track down the defendants who fled the scene after the incident, they said.
The BJP alleged that the assailants followed Sanjith, a native of Elappully, in a vehicle, hit his two-wheeler and when he fell they shot him dead in front of his wife.
In condemning the murder of the RSS worker, BJP state chairman K Surendran claimed it was a “planned murder” and blamed the failure of the police and state government for such incidents to occur in the state.