The pair both had the drug hidden in their underwear.
In September 1987 Lorraine Cohen was sentenced to death and her son to life imprisonment. Aaron Cohen was only spared the death penalty because of his young age.
Both appealed against their sentences and the elder Cohen's was reduced to life imprisonment.
After surviving a battle with breast cancer while in prison, Lorraine Cohen successfully obtained a pardon with the help of Mr Singh. They were released in 1996.
Mrs Cohen was not available to comment last night.
Mr Singh, a father of five, was one of Malaysia's most prominent lawyers. He was also a politician and former national chairman of the Democratic Action Party.
His most recent high-profile case was that of Malaysian opposition leader Anwar Ibrahim, charged with and jailed for sodomising a male former aide.
Ibrahim described Mr Singh as "an indefatigable fighter for justice" in a tribute on Twitter.
In 2005 Mr Singh survived a car accident, but was wheelchair-bound. His disability did not stop his legal and political careers.
Thousands of people lined the streets as his coffin was transported to a state funeral service.
In his eulogy, Penang Chief Minister Lim Guan Eng said Mr Singh dedicated his life to the legal profession, fighting for justice and upholding constitutional and human rights.
Karpal Singh
• Malaysian lawyer and politician.
• Admitted to the Penang Bar in 1969.
• Leading opponent of the death penalty in Malaysia.
• Successfully defended at least 10 foreigners on serious drug charges which carry a mandatory death sentence.
• Defended New Zealand heroin smugglers Lorraine and Aaron Cohen and was instrumental in their pardon.
• Also defended Australian drug trafficker Kevin Barlow who was executed in Malaysia in 1986.
• Represented former deputy prime minister Anwar Ibrahim during his two sodomy trials.
- Staff reporter
