Kerala:�An 85-year old man allegedly killed his wife and ailing son in their house here for using the air conditioner disregarding his diktat against it to bring down the rising power bill, police said. Paul Painadathu also allegedly made an attempt to commit suicide after fatally attacking his 74-year old wife and 54-year old son with a sharp edged iron bar at around 1 AM. The octogenarian, a retired railway official, has been detained and investigations were on, police said. Paul telephoned his other son working in Qatar and informed him about the incident and also told him that he was going to commit suicide. The panic-stricken son immediately telephoned their relative staying in the neighbourhood, who in turn alerted the police. According to police, Paul had warned against excessive use of air conditioner in view of escalating electricity bill. But both his wife and son, who had recently undergone treatment for heart problem, ignored his advice and switched on the AC last night, police said. Enraged over this, Paul entered the room in which the two were sleeping and hit them with the iron bar. Both died on the spot. After the incident Paul allegedly tried to kill himself by hanging from the roof but could not climb the ladder due to his old age, police said.