A youth committed suicide after allegedly killing his father and stabbing his mother at Napitkhali village in Mathbaria upazila yesterday. Quoting local people, police said Jahirul Islam, 17, engaged in a heated quarrel with his father, Abdul Jalil, a retired school teacher, over a family matter yesterday afternoon. At one stage, Jahirul hacked his father with a knife, leaving him dead on the spot. As his mother, Firoza Begum, tried to save her husband, the boy stabbed her also.  After the incident, Jahirul ran away and reportedly killed himself by hanging from a tree, about a kilometre from the family home.  Meanwhile, seriously injured Firoza, 45, was admitted to Barisal Sher-e-Bangla Medical College Hospital for treatment. Khandakar Mostafizur Rahman, officer-in-charge of Mathbaria police station, said they are trying to find the reason behind the tragic incident.