KUALA LUMPUR - Malaysia's highest court on Thursday upheld guilty verdicts and death sentences for three Mexican brothers, a Singaporean and a Malaysian convicted of manufacturing drugs.
The Gonzalez Villarreal brothers - Luis Alfonso, 47, Simon, 40, and Jose Regino, 37 - were arrested in March 2008 in an industrial building in southern Malaysia where police found 30 kilograms (66 pounds) of methamphetamine and equipment for making drugs.
The brothers insist they were working as cleaners and were unaware drugs were being made.
Drug trafficking convictions in Malaysia carry a mandatory sentence of death by hanging.
"Our decision is unanimous. Appeal dismissed against all five defendants. Conviction and sentence affirmed," Federal Court justice Zulkefli Ahmad Makinudin, speaking on behalf of a panel of judges, told the court in Malaysia's administrative capital of Putrajaya.
The men were sentenced in May 2012 and the ruling was affirmed a year later by an appeals court.
The brothers are from Culiacan, the capital of Mexico's northwestern state of Sinaloa, bastion of the powerful Sinaloa drug cartel.
The brothers, dressed in white prison trousers and white shirts with red sleeves, took the decision calmly, even managing to smile as they were led from court.
The Mexican foreign ministry has said it had "repeatedly expressed (to Malaysian authorities) Mexico's position against capital punishment".
The defendants included Singaporean citizen Lim Hung Wang, 56, and Lee Boon Siah, 51, of Malaysia.
The decision exhausts all normal court options for the defendants, but defence lawyer Hisyam Teh Poh Teik said they planned to seek a last-ditch judicial review of the case by the Federal Court.
Failing that, they may consider seeking a royal pardon from Malaysia's figurehead monarchy, he said.
Success in both options is extremely rare.
Besides arguing that the brothers were innocent cleaners, the defence said drugs seized as evidence had been improperly handled.
But Zulkefli said "in our view there was no break in the chain of evidence".
Prosecuting attorney K. Mangaiarkarasi said the factory in southern Johor state was locked with no one inside apart from the five condemned men at the time of a police raid, and that traces of crystal methamphetamine were found on their clothing.
"They were not cleaners, as they claim," she said. "There is massive evidence to show that they were manufacturing methamphetamine."
Malaysia has more than 900 people on death row, the government said last year. Amnesty International has said drug offences are believed to account for more than 70 per cent of death-penalty convictions.
Executions are believed to be rare, however; Amnesty reported earlier this month that two executions took place in 2014.
Malaysia's government does not publish information on executions.