A minke whale that had strayed deep into the Amazon rainforest has been found dead.
Local people helped in attempts to rescue the whale
The 5.5m (18ft) whale was believed to have become lost in the Amazon's many tributaries after leaving the Atlantic more than 1,600km (1,000 miles) away.
Attempts by conservationists and volunteers to catch the animal and transport it back to sea failed.
Biologists have conducted an autopsy on the minke whale to determine the cause of death.
The whale was first spotted last week in the Tapajos River, a tributary of the Amazon, where locals reported seeing a mysterious animal in the water.
Experts say that it could have been in the area for up to two months after getting lost on entering the massive river delta.
Experts said the animal would be stressed and disorientated
It had beached itself on sandbanks several times and had been freed once by rescuers.
Local people were seen splashing its back with water to protect it from the Amazonian heat.
On Sunday, biologists and volunteers tried to contain the animal, said to weigh 12 tonnes, in a small area of river before taking it back to sea by boat.
But it broke away from the area and its corpse was spotted on Tuesday by local people who reported it to the authorities.
Experts had earlier said that although whales could survive many months without food, the animal would be disorientated.
Milton Marcondes, a veterinarian with the Brazilian Humpback Whale Institute, which was involved in the rescue attempt, said that the whale would be stressed and could easily become ill.
"We can't forget this animal has been away from its natural habitat for a long time," he told the Associated Press.