Singapore is due to hang a man for abetting an attempt to smuggle cannabis into the country.
Tangaraju Suppiah’s family have pleaded for clemency over the planned execution while activists have alleged he was convicted on weak evidence.
The 46-year-old was sentenced to death in 2018 after a judge found he was the owner of a phone number used to coordinate an attempt to traffic 1kg of cannabis.
He is due to be executed on Wednesday, reported the BBC.
Human rights groups have raised concerns about the process of Mr Suppiah’s conviction, alleging he was not given adequate access to an interpreter and had to argue his last appeal on his own because his family was unable to secure a lawyer.
Singapore officials have insisted that he had access to legal counsel throughout the process.
His case has been championed by Sir Richard Branson, while his family have personally appealed to Singapore’s president Halimah Yacob for clemency.
Speaking at a news conference, his sister Leelah Suppiah said: “I know that my brother has not done anything wrong. I urge the court to look at his case from the beginning.”
The case centres around a delivery of cannabis from Malaysia to Singapore in 2013. The country has some of the world’s strictest drug laws, and the death penalty is enforced for drug trafficking.
Mr Suppiah was not caught with the delivery, but prosecutors said he was responsible for coordinating it.
He claimed he was not the person communicating with others connected to the case. Of two phone numbers the prosecution tracked to him, he said he had lost one of the phones and denied owning the second one.
In his last appeal, the judge decided he was responsible for coordinating the delivery - making him ineligible for a lesser sentence.
Sir Richard has condemned the death sentence, saying Singapore could be about to kill an “innocent” man, and calling it “shocking” on multiple levels.
“This was largely a circumstantial case that relied on inferences,” he said.
“Investigators and prosecutors acted on the fact that his mobile numbers were stored on the actual drug traffickers’ phone, interpreting phone records and text messages as “proof” of his involvement.
“Tangaraju’s alleged co-conspirator – who was actually caught in possession of the drugs – pleaded guilty to a non-capital offence.
“The other three people connected to the case were “discharged not amounting to an acquittal” by the prosecution. Tangaraju himself has maintained his innocence from the very beginning of his ordeal.”
Singapore’s Home Affairs Ministry accused the billionaire of “disrespect” for Singapore's criminal justice system, and said the death penalty was “an essential component" in keeping the country safe.
The case comes around a year after the execution of Nagaenthran Dharmalingam, a Malaysian with learning disabilities who was convicted of drug trafficking in 2010.
It sparked international controversy as Mr Dharmalingam was assessed by a medical expert to have an IQ of 69 - a level that indicates an intellectual disability.