Supakij Insawang, 23, was found guilty of knifing 21-year-old Chaiyaporn Jaroonpak on a bus with a 20-centimetre-long knife before throwing him out of the moving bus.

Chaiyaporn died of a knife wound to his heart and head injuries caused by the fall. The brutal attack took place before hundreds of commuters waiting at a bus stop on Rama IV Road in downtown Bangkok and made headlines in newspapers.

Supakij was a former student at Rajamangala University of Technology Tawan-Ok's Uthen Tawai campus, while Chaiyaporn was studying at the Pathumwan Institute of Technology. Students from these schools have engaged in frequent brawls.

Two witnesses, who worked for the Monthien Hotel, testified against Supakij. They said Supakij deliberately moved past groups of passengers on the crowded bus to attack Chaiyaporn.

The court dismissed Supakij's excuse citing self defence, saying that his testimony that Chaiyaporn bullied him first and he only knifed the victim, after finding a knife on the floor by chance, in self defence as unconvincing.

Supakij provided some useful information during the trial, so his original life term was commuted to 33 years in jail, although he pleaded not guilty during the trial all along.