CNN  — 

A man with intellectual disabilities was executed in Singapore on Wednesday, his family’s lawyer said, after a long campaign for clemency failed, putting the city-state’s zero-tolerance drug laws back under scrutiny.

Nagaenthran K Dharmalingam, a 34-year-old Malaysian citizen, was arrested in 2009 for bringing 42.7 grams (1.5 ounces) of heroin into Singapore. He was convicted and sentenced to death in 2010.

Dharmalingam’s brother was told by a prison official that the execution had been completed on Wednesday, his family’s lawyer, N. Surendran, told CNN.

“His brother is waiting to collect his body and take it back to their hometown, Ipoh in Malaysia,” Surendran said.

Dharmalingam’s case drew international attention – including from the United Nations, Malaysia’s Prime Minister Ismail Sabri Yaakob and British billionaire Richard Branson – who decried the court’s proceeding despite his intellectual disability. A psychologist assessed his IQ to be 69.

His lawyer filed multiple appeals to overturn the execution, arguing that Dharmalingam should not have been sentenced to death under Singaporean law because he was incapable of understanding his actions.

But a Singapore court rejected a final appeal from Dharmalingam’s lawyer last month, saying there was “no admissible evidence showing any decline in the appellant’s mental condition after the commission of the offense.”

On Tuesday, a Singapore court turned down a legal challenge by Dharmalingam’s mother, clearing the way for the execution, according to Reuters. At the end of the hearing, Dharmalingam and his family wept as they grasped each others’ hands through a gap in a glass screen, Reuters reported, adding that Dharmalingam’s cries of “ma” – which means “mother” – could be heard in the courtroom.

Anti-death penalty group Reprieve said Dharmalingam’s “name will go down in history as the victim of a tragic miscarriage of justice.”

“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,” Reprieve director Maya Foa said in a statement.

“Nagen’s last days were spent, like much of the last decade, in the torturous isolation of solitary confinement. He had to seek the court’s permission to hold his family’s hands one final time yesterday. Our thoughts are with Nagen’s family, who never stopped fighting for him; their pain is unimaginable.”

Singapore has some of the strictest drug laws in the world.

Trafficking a certain amount of drugs results – for example, 15 grams (0.5 ounces) of heroin – in a mandatory death sentence under the Misuse of Drugs Act. It was only recently – and after Dharmalingam’s case began – that the law was amended to allow for a convicted person to escape the death penalty in certain circumstances.

Dharmalingam spent a decade on death row and during that time his condition further deteriorated, according to his lawyer.

About 300 people held a candlelight vigil in a Singapore park on Monday to protest against Dharmalingam’s impending execution, according to Reuters.