Nagaenthran Dharmalingam, a 34-year-old Malaysian who had an IQ of 69, was hanged yesterday despite a widespread plea for clemency.

He was arrested in 2009 at the age of 21 with 43g of heroin, worth a few thousand dollars on the streets, as he entered Singapore. According to his lawyers, he had agreed to be a drug mule after a smuggler in Malaysia threatened him and his girlfriend.

He was found guilty in 2019 and sentenced to death, the mandatory sentence for drug trafficking in the jurisdiction. Exemptions may be given for the intellectually impaired.

“It is unbelievable that Singapore proceeded with the execution despite international appeals to spare his life,” his sister Sarmila Dharmalingam said from Malaysia.

The United Nations Office of the High Commissioner for Human Rights called for a stay of execution but all appeals for clemency were dismissed by Singapore’s president and courts.

“Nagaenthran Dharmalingam’s name will go down in history as the victim of a tragic miscarriage of justice,” said Maya Foa, director of Reprieve, a group that campaigns against the death penalty.

“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.”

The execution followed a final appeal on Tuesday. Mr Dharmalingam grasped his family’s hands through a gap in a glass screen as they wept, while his cries of “ma” were heard in the courtroom.