On Thursday, a Malaysian high court sentenced five people, including three Mexican brothers, to be hanged by the neck for drug trafficking.

Jose Regino Gonzales Villarreal, 33, Simon Gonzales Villarreal, 36, and Luis Alfonso Gonzales Villarreal, 44, are from Sinaloa, a fertile coastal state that has long been a hub for Mexico's drug trade. The brothers are the first Mexicans ever to be convicted for drug trafficking in Malaysia.

Also convicted were a painter from Singapore and a crane operator from Malaysia, reports Chinese news outlet Xinhua.

The men were first arrested four years ago at a remote drug manufacturing facility in the state of Johor. Police found 63 pounds of methamphetamine on site, with traces of the illegal substance on the men's clothes.

In court, defense attorneys argued that incriminatory evidence had been tampered with, citing a chemist's testimony that some items he had analyzed appeared to have been altered.

The defendants claimed that they had been at the facility simply to clean it, not to manufacture drugs. But on Thursday, Kuala Lumpur High Court Judge Mohamad Zawawi ruled that they were aware and involved in the activity of drug-making, beyond any reasonable doubt.

The brothers from Mexico, who have no previous criminal records, expressed surprise at the verdict. We are very sad, said Luis Alfonso Gonzales Villarreal to the Associated Press. We thought we would be acquitted.

A drug trafficking conviction in Malaysia carries a mandatory death penalty. The country has been tough on drug trafficking since the 1980s, when the government began to consider heroin a national threat. Beginning in 1983, a series of laws has instituted severe punishments for drug-related offenses and increased the number of drug rehabilitation centers, with the goal of eradicating drug addiction problems by 2015.

Amnesty International reports that Malaysian courts sentenced at least 114 people to hang by the neck until dead in 2011, although no official count has been published.

More than half of known death sentences were for possession of illegal drugs above certain specified quantities, an offense which carried the mandatory death penalty, said the report.

Defendants in such cases faced charges of drug trafficking. Under the drug laws, they were presumed guilty unless they could prove their innocence, which contravened international fair trial standards.

All five men convicted on Thursday are expected to appeal their conviction.