A Thai Criminal Court on Wednesday sentenced a local drug lord to life imprisonment and his son to death for selling 20 kilogrammes of crystal methamphetamine, a court official said.

His wife, Asama Saenlee, 67, also got life jail term for same offence.

Laota Saenlee, 77, long considered a drug lord in Thailand’s Northern City of Chiang Mai, and four other suspects were arrested in a sting operation in October, 2016.

They were then charged with sales of illicit drugs and illegal possession of guns and bullets.

Laota and his wife, Asama Saenlee, 67, were handed life imprisonment instead of a death penalty typical for this type of drug offence, the court official, who was not authorised to speak to media, said.

The pair’s more lenient verdict was due to their confessions, a common practice in the Thai judicial system.

However, Laota’s 41-year-old son, Vijarn Saenlee, was sentenced to death as he pleaded not guilty, the official said.

Laota has long been suspected of being a key drug lord in the Golden Triangle, a border area shared by Thailand, Myanmar and Laos notorious for its opium cultivation and rampant drug trafficking.

He was known as an aide to Khun Sa, a Shan drug kingpin known in Myanmar as the “Opium King’’ who died a decade ago.

An ethnic Lisu, a minority from south-west China, Laota once joined anti-communist Kuomintang in the 1970’s.

Laota and his family were given 30 days to appeal, the court said.