Pol Lt Col Thanom Thongpan of the Thalang Police was informed of the incident at about 7pm.
Police along with Srisoonthorn Municipality rescue workers and a Thalang Hospital ambulance soon arrived at the scene, a room on the second floor of Building 56 of the Eua Arthorn government housing complex in Moo 1, Srisoonthorn.
Inside the room they found Somkiat Janhorm with multiple stab wounds to the right side of his chest.
He was unconscious when discovered. The rescue team performed CPR and urgently transported him to Thalang Hospital, where he was later pronounced dead.
According to police, preliminary investigations revealed that six people lived in the apartment.
The nephew frequently argued with his uncle, and this time, the argument escalated. The nephew, in a fit of rage, stabbed his uncle in the right chest and back before fleeing with his sister.
Police detained the 15-year-old. The boy is currently under investigation at Thalang Police Station.
Mr Somkiat’s wife, La-or Janhorm, 54,reported that the nephew had not been taking his medication for his condition and was prone to severe mood swings. She had intended to take him to see a doctor today.