Along a steep path strewn with clothes and food wrappings a low cage had been built, too small for a person to stand up in.
"These structures were believed to be used as human cages," said senior Malaysian policeman Mohammad Bahar Alias.
The scene described by journalists taken to the camps along Malaysia's northern border with Thailand by police has shocked many Malaysians.
"People were tortured, caged and robbed of their human dignity - in our own backyard," said Malaysian opposition MP Charles Santiago.
"I will push for a royal commission of inquiry so that all Malaysians are informed, [and] for those responsible to face the law and, more importantly, that this never happens again," he said.
Police have found 140 shallow graves at the 28 people smuggler camps strung along a 50-kilometre stretch of the border in Malaysia's Perlis state, far more extensive than Malaysia announced on Sunday.
Joel Millman, a spokesman for the International Organisation for Migration told a news briefing in Geneva that the body's representative in the region "predicts hundreds more [bodies will] be found in the days to come."
Late on Tuesday police exhumed the first of what are believed to be hundreds of Rohingya Muslims fleeing persecution in Myanmar and Bangladeshi migrants.
The grisly discoveries have exposed a hidden network of jungle camps run by ruthless people-smugglers who held migrants and asylum seekers captive while extorting money from their relatives.
If money was paid the captives were allowed to enter Malaysia, where many ended up working as cheap unregistered laborers.
But many others disappeared and mass graves on both sides of the Malaysia-Thai border now reveal their fate.
"If an individual's family did not pay, those staying long in camps were tortured, beaten and deprived of food," Mr Millman said.
An Associated Press reporter saw a tiny orange slipper partly buried on a slope at one of the Malaysian camps, indicating children were held there.
Police said the camp could hold 300 people.
A Reuters journalist said the location was a perfect setting for smugglers to ply their trade.
An hour's trek form the nearest road, prisoners could be kept alive with water from a stream running through a gully and there was good mobile telephone reception from Thailand so the smugglers could communicate with accomplices across a lucrative trafficking supply chain.
Malaysia's police chief Khalid Abu Bakar said the camps were thought to have been occupied since 2013 and two were "only abandoned between two and three weeks ago."
Residents in the area said they were used to seeing migrants.
"They are often starving, not eaten for weeks," said Abdul Rahman Mahmud, who runs a small hostel in the area.
"They eat seeds or leaves or whatever they could find. It's a real pity and sad to see this," he said.
Malaysia's Home Minister Zahid Hamidi said police are probing the possibility that government officials, including some from the Forestry Department, may be involved in trafficking syndicates.
Several Malaysians have been arrested.
In Thailand where mass graves were found in early May, dozens of people, including local politicians and police, have also been arrested in a crackdown on human trafficking.
The crackdown prompted traffickers to abandon thousands of migrants and asylum seekers in overloaded boats that had made the perilous journey across the Bay of Bengal in a humanitarian crisis that caused international outrage.
Several thousand could still be adrift at sea, refugee advocates fear.
More than 15 nations, including Australia, are due to discuss the crisis at a Thailand-hosted meeting in Bangkok on Friday.
REPORTERS ON THE RUN
Phuketwan journalists Alan Morison and Chutima Sidasathian will be in Bangkok for the Special Meeting on Irregular Migration in the Indian Ocean and available on the sidelines for interviews about the precedent-setting military versus media criminal defamation case brought against them by the Royal Thai Navy.
''As long as the Royal Thai Navy pursues these false charges, reporters and editors in Thailand and around the world cannot and will not accept the military government's word that it understands the universal principles of media freedom and democracy,'' says Morison.
Morison and Khun Chutima are obliged to begin serious preparations for their July trial from Monday, June 1. Please call Khun Chutima (''Oi'') on 089 4725117 to arrange an interview sometime between 2pm Thursday and noon Saturday.