TARN TARAN:, May 22 -- A mentally challenged man allegedly killed his sister, a goat and the family's pet dog at his home in Sabhra village falling under Patti sub-division of Tarn Taran district. The accused also critically injured his mother, the police said. According to police, Rasal Singh, who is mentally challenged, first got into an argument at home and killed a goat. He later killed the family's pet dog and subsequently attacked his sister, Sandeep Kaur, 26, by striking her on the head with a spade, leading to her death. Kaur, a married woman from nearby Tut Pangala village, had come to her parental home to inquire about her brother's condition. Mukhtiar Singh, father of the accused, said he was away from home at the time of the incident and had no knowledge of what had happened. When he returned, he found his daughter dead and wife critically injured. Tarn Taran DSP Parvesh Chopra said the accused has been arrested by Sadar Patti police. A case has been registered on the statement of the victim's father....