The female red kangaroo that escaped from Chiang Mai Zoo was found dead in Doi Suthep-Pui National Park on Thursday afternoon.
Park rangers and Chiang Mai Zoo staff found the carcass in a stream at 2.30pm.
The two-year-old kangaroo escaped from the zoo on Wednesday morning, while keepers were cleaning its cage.
It was seen hopping uphill on a road towards the Doi Suthep mountain on Wednesday. The search was suspended on Wednesday night after rescuers found its footprints and some blood stains.
The search resumed and was expanded on Thursday morning.
The director of the zoo said it was likely that the kangaroo drowned because the section of the stream was lined with boulders that were covered with plants.
The kangaroo might have accidentally fallen into the water and could not get up the banks, he said.
There were small scratch marks on the carcass, but no big wounds or bite marks, so apparently the kangaroo was not attacked, he said.
The location of the carcass was 1.8 kilometres from the zoo.
