Four workers died Tuesday of asphyxiation at a construction site after they entered a septic tank near Sukkaliyur in Tamil Nadu’s Karur district, police said. The body of the fourth worker was however retrieved only Thursday when the rescue personnel were filling water in the tank to clear the poisonous gas, they said. The deceased are Mohanaraj, 23, Sivakumar, 35, Rajesh, 38, and Gopal, 35. According to police, the incident took place at an under-construction house where the mason had engaged the workers to construct a dry toilet. “He had asked the workers to remove the wooden planks supporting the septic tank. Mohanaraj and Sivakumar who were involved in the construction work were told to clean the septic tank. They fell unconscious inhaling the toxic gas. Rajesh who had rushed to their rescue also fell unconscious,” they said. The Fire and Rescue Personnel and the local police who rushed to the spot pulled out the three men from the tank and sent them in an ambulance to a nearby hospital. However, the doctors declared them dead on arrival. The police suspected that methane poisoning was the cause of the deaths. The relatives of the deceased staged a dharna outside the hospital urging them to provide compensation to the family of the victims. They refused to receive the body until their demands were met. After the police personnel pacified the mob and assured them of due action, they accepted the body. Meanwhile, the Fire and Rescue personnel searched for Gopal based on the complaint of his brother that Gopal has been missing for two days. His body was recovered from the septic tank premises. A senior investigation officer told indianexpress.com that the owner of the house Gunasekara, a lawyer, is absconding while the mason has been nabbed. When asked why it took the officers another two days to find the fourth person, the officer said that the mason had misguided the police. “He initially said only two persons were inside and later one who attempted to help them also got trapped inside. The officers were involved in getting those people out of the tank. Later, on Thursday, when the rescue men were filling the water inside the tank to emit the poisonous gas, they found the fourth body,” the police officer said. The Karur police booked Gunasekaran and the mason Karthik under section 284 (negligent conduct with respect to poisonous substance) and 304(II) (culpable homicide not amounting to murder) of the Indian Penal Code. Since two of the four deceased belong to the SC community the accused have also been booked under the Scheduled Castes/Scheduled Tribes (Prevention of Atrocities) Act. The police said that though the workers were not used to lifting the human waste from the tank, making them indulge in constructing the septic tank is an offence and it amounts to provisions under the Prohibition of Employment as Manual Scavengers and their Rehabilitation Act.