Story highlights The drug lord and three members of his gang say they will appeal the verdict

The men were convicted in the murder of at least 12 Chinese sailors in Thailand

Thai authorities found the corpses and about 1 million amphetamines in 2011

A Chinese court has condemned to death four men for the killing of at least 12 Chinese sailors on the Mekong River in the northern Thai province of Chiang Rai.

One of the men sentenced Tuesday is a drug lord named Naw Kham, Chinese state news agency Xinhua reported. The other three were members of his gang.

Thai authorities discovered the gruesome murder scene in October 2011 after boarding two cargo ships that had come under gunfire. They found nearly 1 million amphetamines and 12 dead bodies, some with their hands bound. One sailor was missing.

Two additional gang members received death sentences with reprieves and will serve eight years in jail.

All of the men, who faced charges of homicide, hijacking, kidnapping and drug trafficking, said they would appeal the verdict.