A worker of a right-wing Hindu outfit has been arrested in connection with the alleged attack on a CPI(M) leader's son and his journalist daughter-in law during a shutdown called by the outfits over Sabarimala in Kerala yesterday. The CPI(M) had alleged that the couple was attacked by activists belonging to the Sangh Parivar. Right-wing Hindu outfits had observed a dawn-to-dusk hartal in Kerala yesterday in protest against the "preventive detention" of Hindu Aikya Vedi state president P Sasikala, who was on a pilgrimage to the Sabarimala Lord Ayyappa temple.