Despite launching a full-scale land and sea search for Valentina Novozhyonova, authorities have so far failed to find the 23-year-old tourist, who checked into a hotel on Koh Tao on February 11 and went missing four days later.

The search team found five pieces of what was thought to be human flesh and bone at the location where she is thought to have gone snorkelling. A green vest and snorkelling goggles were also discovered about 400 metres from the Ao Chalok Ban Kao beach resort where she was staying.

All of the evidence was sent for DNA tests at the Institute of Forensic Science of the Royal Thai Police. However, the results showed the flesh was not human and a DNA sample from the cloth did not match the missing woman.

Following the results, police plan to hold a meeting to discuss the next steps in the search. They are also waiting to question a friend of the woman who has promised to return from the Philippines to meet them next week.

Meanwhile, Surat Thani Provincial Police commander Pol Maj Gen Apichart Boonsriroj said the authorities still put more focus on a water accident as the likely cause of the Russian’s mysterious disappearance.

“We still give more importance to a water accident rather than other causes. It’s not about crime because Valentina liked to do free diving alone,” he said.

“She wanted to beat her personal record of diving, set at 22 metres under the sea.

“We’ve tried to update the Russian embassy about the search even though they didn’t ask us to do that. We did not find [any] more objects of evidence this morning,” Apichart said on Friday.