New Delhi, July 28: Delhi Police on Saturday said a manhunt has been launched to find the missing father of three dead girls after a magisterial inquiry found that hunger may not have caused their deaths as was reported earlier but an "unknown medicine" they were given may have killed them.The suspect, Mangal Singh, is said to be an alcoholic who was jobless after his e-rickshaw was stolen. from east Delhi's Mandawali neighbourhood."On the night before the incident, July 23, Mangal, the father of the children, had given all the three children some unknown medicine with hot water and the children died in the morning," SDM Arun Gupta said in his report."The fact that Mangal Singh has not returned since...raises an element of doubt in the matter and require further investigation," the Sub-Divisional Magistrate said in his report that was given to the government on Friday.The three sisters -- aged two, four and eight -- were discovered unconscious in their one-room house in Mandawali area on Tuesday. They were taken to the Lal Bahadur Shastri (LBS) Hospital where they were declared brought dead.Autopsy reports of the three girls concluded that the deaths were a clear case of starvation. Doctors at the hospital, who performed the autopsy, ruled out any other cause of their death, saying no traces of food were found in their stomachs.However, the magisterial probe discovered that the three girls were suffering from loose motions and vomiting which may have been due to some stomach infection."They were not provided adequate ORS solution or proper medication which may have caused dehydration," Gupta said in his report.The probe has also discovered that the eldest of the three children, Mansi, appeared ill on Monday and vomitted. She was also provided mid-day meal at her school but she could not consume much due to her illness. It was also found that Rs 1, 805 was deposited in Mansi's bank account.Based on Gupta's report, results on viscera and post-mortem collected by the hospital that mentioned that the children had died to starvation is still awaited. The police have been asked to convince the mother of the children - who is mentally unstable - to depose before the investigators.Gupta has "proper and deeper investigation" into the matter by Delhi Commissioner of Police, East, Pankaj Kumar Singh.