PHNOM PENH - The seven-inch scar runs diagonally across the left flank of his skinny torso, a glaring reminder of an operation he hoped would save his family from debt but instead plunged him into shame.
Chhay, 18, sold his kidney for US$3,000 (S$3,826) in an illicit deal that saw him whisked from a rickety one-room house on the outskirts of the Cambodian capital Phnom Penh to a gleaming hospital in the medical tourism hub of neighbouring Thailand.
His shadowy journey, which went unnoticed by the authorities two years ago, has instigated Cambodia's first-ever cases of organ trafficking and the arrests of two alleged brokers. It has also raised fears that other victims hide beneath the radar.
At the corrugated iron shack he shares with nine relatives, Chhay says a neighbour persuaded him and a pair of brothers - all from the marginalised Cham Muslim minority - to sell their kidneys to rich Cambodians on dialysis. "She said you are poor, you don't have money, if you sell your kidney you will be able to pay off your debts," the teenager told AFP, requesting his real name be withheld.
Identical stories have long been common in the slums of India and Nepal, better-known hotspots for traffickers. Up to 10,000, or 10 per cent, of the organs transplanted globally each year are trafficked, according to the latest World Health Organisation (WHO) estimate.
But on discovering the broker earned US$10,000 for each kidney they sacrificed, the donors filed complaints, alerting police in June to a potential new organ trade route.
"Kidney trafficking is not like other crimes... If the victims don't speak up, we will never know," said Phnom Penh's deputy police chief Prum Sonthor.
In July his force charged Yem Azisah, 29 - believed to be a cousin of the sibling donors - and her step-father, known as Phalla, 40, with human trafficking.
The pair are being detained and await trial.
Trafficking is a widespread problem in impoverished Cambodia and police routinely investigate cases linked to the sex trade, forced marriage or slavery - but this was the first related to organs.
"This is easy money that earns a lot of income, so we are worried," said Mr Prum, adding there were at least two other Cambodian donors taken to Thailand who had not filed complaints.
The complicity of donors, whether compelled by poverty or coerced by unscrupulous brokers, makes it an under-reported crime that is difficult to expose.
In August media reports emerged about new alleged organ trafficking cases at a military hospital in Phnom Penh.
Mr Prum, who investigated the case, said it was a training exercise between Chinese and Cambodian doctors, using voluntary Vietnamese donors and patients.
But he was unable to rule out whether money changed hands.