South Korean prosecutors on Thursday requested an appellate court to hand a 25-year prison term to a 20-year-old over the death of a mentally disabled 18-year-old, who died after the accused pushed him into the sea for losing a game.

Prosecutors want the defendant convicted of murder, after a lower court found him guilty only of a lesser offence.

He pushed the victim into the sea in Mokpo, South Jeolla Province, on Feb.1. The defendant lured the victim to the port by suggesting to go fishing, as the two were acquainted with each other.

The defendant suggested a game of rock paper scissors, knowing that the victim only played the game in a pre-determined pattern, where the loser would jump in the water. The victim refused to go in the water after he lost but the defendant forcibly pushed him anyway, while his younger accomplices stopped the victim from running away and filmed with smartphones.

The prosecutors said that the defendant had at least willful negligence involved in the victim's death, saying that an earlier court ruling was wrong to sentence him to a four-year jail term for death resulting from violence. The earlier ruling had cleared the defendant of the murder charge, on grounds that the victim's death appears to have been an unintended result of a prank gone wrong.

The underage accomplices of the defendant were found guilty of aiding and abetting an assault.

The defendant had settled with the victim's bereaved families, and has claimed that he did not intend to kill the victim, who he said was a close friend.

The court will reach a verdict for the defendant at 2 p.m. on Dec.19.