Cambodia's Supreme Court on Wednesday upheld the sentences of four men, including a former commune chief, for their involvement in a 2014 grenade attack in Phnom Penh that killed the intended target’s 11-year-old son and wounded five others.

In July 2015, the Phnom Penh Municipal Court sentenced the group of men to 30 years to life in prison for conspiring to murder Sorn Sin, who was engaged in both a political and land dispute with the Kok Roka commune chief at the time, Phy Nop, who drew up the plan to throw a grenade at Sin’s family home in Sen Sok district in October 2014.

Nop was found guilty of planning the assassination and was sentenced to life in prison, a decision that was upheld on Wednesday.

Noun Samrith, one of his accomplices, was also handed a life sentence for throwing the grenade, which exploded just two metres from Sin and his relatives as they ate dinner on their patio. Sin's son was killed, while he and four of his relatives were seriously injured during the explosion.

Eng Dalin, who drove the motorbike carrying Samrith, is serving a 30-year sentence, as is Pov Bunthoeun, who hired Dalin and Samrith for the job.

Soeung Panhavuth, one of the presiding judges on Wednesday, said Nop and Bunthoeun were not present in court due to illness.

During the 2015 trial, Nop confessed to having plotted the murder because he took exception to Sin’s allegations that he had bought votes and bribed the Phnom Penh Municipal Election Commission.

Samrith told the Phnom Penh Municipal Court in 2015 that he had been hired for $5,000, but was only paid half his share for having miss the intended target.

Bunthoeun at the time also admitted his involvement to the court and said Nop had promised him $10,000.

In its 2015 decision, the court also ordered Nop to pay around $180,000 in compensation to the victims.