Singapore's top court Tuesday dismissed a mentally disabled Malaysian man's last-ditch appeal against a death sentence. Nagaenthran K. Dharmalingam was arrested in 2009 for trafficking a small amount of heroin into the city-state, which has some of the world's toughest drugs laws, and handed a then mandatory death sentence the following year. Supporters say he has an IQ of 69 -- a level recognised as a disability -- and was coerced into committing the crime. But authorities have defended his conviction, saying that legal rulings found he "knew what he was doing" at the time of the offence. Singapore maintains the death penalty for several offences, including drug trafficking and murder, and insists it has helped to keep the city-state one of Asia's safest places. IMAGES AND SOUNDBITES