A 29-year-old mentally unstable woman from Surendranagar district killed her three-year-old daughter and then committed suicide on Saturday. Following the incident,the Halvad police have registered a case of murder and further investigations are on. The deceased have been identified as Pushpa Patel (29) from Samli village of Halvad taluka in Surendranagar and her three-year-old daughter Drishti. According to the police,the incident happened on Saturday morning when the woman was washing clothes. Suddenly,she lost her mental control and started hitting the girl with a wooden bat. Soon after that,she consumed acid kept inside the toilet in the house, said Sub Inspector B J Kubavat,who is investigating the case. The two were soon rushed to a hospital in Halvad,but both died on the way. Kubavat said that it was Pushpas second marriage with Rajni and the girl was from her first marriage. During her last moments,Pushpa said she wanted to commit suicide because of her mental condition and that she killed her daughter because she did not want her to suffer after her death, he said.