Like most prisons, Bang Kwang Central reeks of decay. But the fetidness of the "Bangkok Hilton", as it is known by inmates, is more indicative of the soul of the place than the damp edifices that contain the men. Built in the 1930s to hold 3500, the maximum security prison in Thailand's biggest city now houses about 8000 inmates, who have been sentenced to more than 25 years each, as well as hundreds awaiting the outcome of their pending appeals, or execution. Leg irons provide a means of status identification: new inmates wear theirs for the first three months, whereas those on death row have their shackles permanently welded on. Fates are determined by will or whim -- a royal birthday here, a public holiday there. The stroke of a monarch's pen determines who shall live, die or be released. And in the interim both the panacea for and consequence of not knowing is insanity: the inmate's survival guide. At the time of his arrest for heroin trafficking, South African Alexander (Shani) Krebs was 34 years old. Initially condemned to death, his sentence was commuted to 100 then 40 years. He has not spent a nano-second in a democratic South Africa, having been arrested a day before the elections in 1994. Over the years he earned the tragic reputation of being the longest-serving farang, or foreigner, in Bang Kwang. But on December 5 Thailand's monarch, King Bhumibol Adulyadej, benevolently issued an amnesty of sorts, courtesy of his birthday, to all farangs convicted of drug offences. In Thailand the seventh cycle, or 84th birthday, is a significant milestone for the monarchy and special celebrations are organised for the entire year. For the foreign inmates it means that one-sixth of their sentences has been reduced. For prisoners incarcerated since 1994, like Krebs, it signals an early release. Although most of the 11 convicted South African drug mules in Thailand have been incarcerated for more than 15 years, it is unclear who else will be released with Krebs. And South Africa's department of international relations and co-operation is not providing answers. What is certain, according to his family, is that Krebs will be released on April 22 -- eerily, almost 18 years to the day of his arrest. On Facebook, where a 751-strong support group was established in 2008, Krebs's friends have been relentlessly posting messages of support and daily marking the countdown. "Shani, only 56 days to go ... every day gets brighter. x," writes Sue. "Support our friend in the last steps to victory," says Erwin. There are psychedelic artworks and photo-shopped collages of Krebs on an aeroplane, Krebs giving the thumbs-up, Krebs reunited with his family in Johannesburg. "We wanted Shani to see how much he has been missed and how his loved ones are literally counting the days till he returns," said his sister, Joan Sacks. Since 1994 she has campaigned tirelessly for his release and kept him updated through letters and the occasional five-minute phone calls permitted by the Bang Kwang authorities. Sacks has also set up a website through which prints of his paintings -- Krebs became an accomplished artist during his incarceration -- can be bought. Arrested in Thailand Meeting him in 2009, through a double layer of bars, wire and glass, was akin to staring at the portrait of Dorian Gray. His curly hair had remained youthfully long, his body ripped and his face -- from a distance, at least -- seemed protected from the ravages of age that cleave creases, folds and furrows into the rest of us. He was 49 years old. Krebs wore a crisp white T-shirt and immaculately pressed blue trousers. He had been up most of the night, he said, copiously preparing notes for our first interview. He was charming and cheerful. He refused to divulge details of his incarceration -- the agonising months in solitary confinement, the daily drudge of prison life, the creeping despair that all he might ever do in his life was time. He made no mention of the sweat-soaked bodies crammed into cells measuring six metres by four metres, forced to sleep spoon-like, or the pungency of the open sewerage system, or the cesspool of disease that is Bang Kwang.