SINGAPORE — Singapore on Wednesday executed a Malaysian man convicted of drug smuggling after a court dismissed a last-minute challenge from his mother and international pleas to spare him on grounds he was mentally disabled.

Nagaenthran K. Dharmalingam, 34, had been on death row for over a decade after he was found guilty of trafficking about 43 grams (1.5 pounds) of heroin into Singapore. The city-state's government has said its use of the death penalty for drug crimes is made clear at the borders.

Nagaenthran's family and social activists confirmed the execution Wednesday.

"On this score may I declare that Malaysia is far more humane," his sister, Sarmila Dharmalingam, said. "Zero to Singapore on this."

Nagaenthran's supporters and lawyers said he had an IQ of 69 and was intellectually disabled, and that the execution of a mentally ill person was prohibited under international human rights law.

Singapore courts cited psychiatrists' testimony that he was not mentally disabled and had understood his actions at the time of his crime.

"Nagaenthran Dharmalingam's name will go down in history as the victim of a tragic miscarriage of justice," said Maya Foa, director of nongovernmental organization Reprieve.

"Hanging an intellectually disabled, mentally unwell man because he was coerced into carrying less than three tablespoons of diamorphine is unjustifiable and a flagrant violation of international laws that Singapore has chosen to sign up to," she said.

Nagaenthran and his mother filed a motion Monday arguing that it was unconstitutional to proceed with his death sentence and that he may not have been given a fair trial because the chief justice who presided over his appeals had been the attorney general when Nagaenthran was convicted in 2010, which the filing alleged could be a conflict of interest.

The court dismissed the motion, describing it as "frivolous."

His family said Nagaenthran's body will be brought to their hometown in Malaysia's northern state of Perak for a funeral.

Singapore had halted executions for two years because of the COVID-19 pandemic before resuming them with the execution of a drug trafficker in March.

Anyone found with over 15 grams (0.5 ounces) of heroin faces the death sentence in Singapore, although it can be reduced to life in prison. Attempts to reduce Nagaenthran's sentence or obtain a presidential pardon failed.

Malaysia's leader, European Union representatives and global figures such as British business magnate Richard Branson called for Nagaenthran's life to be spared and used the case to advocate for ending capital punishment.

Human rights group Amnesty International said in a statement that Nagaenthran's hanging "highlights the deep flaws of the death penalty in Singapore and the horror of its continued use."

"The execution of Nagaenthran is a disgraceful act by the Singapore government – ruthlessly carried out despite extensive protests in Singapore and Malaysia and an outcry across the world," said Amnesty International's Asia-Pacific regional director Erwin van der Borght.

According to activists, another Malaysian, Datchinamurthy Kataiah, is scheduled to be executed in Singapore on Friday. He was convicted of smuggling 45 grams (1.5 ounces) of heroin from Malaysia. Singapore doesn't formally announce its hangings.

Copyright 2022 NPR. To see more, visit https://www.npr.org.