A police officer has been suspended as an investigation continues into the mysterious death of Tia Morchor, a famous dog beloved of Chiang Mai University (CMU) students.

The dog went missing from the campus on May 4 and its body was found behind Rajamangala University of Technology Lanna on May 7. Footage from CCTVs on CMU's campus showed the dog being driven on a motorcycle on the night of May 4.

Watchdog Thailand posted a Facebook message saying the Royal Thai Police Office had suspended an officer and launched an investigation. 

The advocacy group praised the decision and indicated there could be more than one person involved in the case as the sacked officer was called “the first suspect”.

No details of the suspect were released but Thairath reported earlier he was a 27-year-old policeman based in San Sai district of Chiang Mai province.

He was charged with theft, torturing animals and disposing of the carcass of an animal, according to Thairath.

Tia Morchor is a darling of CMU students, past and present, along with staff members. One of its well-known activities was to lead new students on a long walk up the Doi Suthep mountain to pay respects to the temple. The dog's age was believed to be eight or nine.

The friendly dog was first spotted on the campus in 2014, and was seen there until its recent disappearance. Tia Morchor was believed to stay at a house near the university at first, but was then given an official home at the Science Faculty. The dog was so popular that it has its own Facebook page, tiadogcmu, and Twitter account, @tiadogcmu. The canine inspired CMU to launch a project to manage and take care of all dogs around the large campus.

A preliminary autopsy conducted  by the university's Animal Hospital found that the dog was hit by a large vehicle, suggesting that it was an accident. But another detailed probe showed the dog might have been killed deliberately.

Fans of Tia Morchor flooded Watchdog Thailand's Facebook page with comments after it posted the news of the police officer's suspension. They demanded legal action against anyone responsible for the death, and posted fond remembrances.