Lucknow: An 18-year-old youth allegedly beat his elder brother to death, assaulted his father and set their house on fire in Jatmalpur village of Gonda district during the wee hours of Sunday, police said.The accused has been arrested. The victim’s body was found a short distance from his home and has been sent for post-mortem. The father of the accused, who also suffered injuries during the attack, was found lying outside the house by villagers.The crime came to light when residents noticed thick smoke billowing from the house. By the time emergency services arrived, the house had been gutted. A buffalo trapped near the structure also died in the blaze.Family members told investigators that the youth had been displaying erratic and aggressive behaviour for some time. He would often pick fights and damage household items, they said, though the family had not sought intervention, assuming the situation was manageable.“Preliminary findings suggest that the youth attacked his brother with a wooden stick, inflicting fatal injuries. After the assault, he allegedly turned on his father before setting the house on fire,” said Wazirganj SHO Vipul Pandey.Police have registered a case and are examining all angles, including the accused’s mental health history.