Talk about holding a grudge.

A 69-year-old Thai marine, Thanapat, is on the run after allegedly shooting a former classmate, Suthud, at a class gathering, a video by Ang Thong News Official reported.

The reason for the murder?

Suthud bullied Thanapat 53 years ago in school.

Thai media Channel 7 News further reported that the incident occurred on Aug. 24, at a restaurant in Ang Thong province where the gathering took place.

Bully allegedly denied actions from 53 years ago

At the time of the gathering, Thanapat had supposedly asked his former bully, Suthud, if he remembered bullying him 53 years ago.

Thanapat allegedly demanded an apology from Suthud.

In response, Suthud denied bullying Thanapat and refused to apologise to him.

This then resulted in Thanapat allegedly pulling out a gun and shooting Suthud in the stomach, with the bullet passing out through his backside.

Ang Thong News Official added that Suthud subsequently died after being admitted to Ang Thong hospital.

Suspect on the run

The police have since requested that the court issue an arrest warrant, given that Thanapat fled the scene after the shooting occurred.

Meanwhile, relatives of Suthud have brought his body to a temple for his funeral.

In expressing his sadness, one of Suthud's brother-in-laws stated that Suthud neither drank nor smoked, and did not have problems with anyone.

Top image screenshots from Ang Thong News Official