Earlier this month, her family received a call from an unidentified person demanding a ransom of 1 million yuan (US$137,800).
Yang’s friends reported the incident to Thai police on Friday, saying they suspected Yang was in danger after they had not heard from her since June 30, when she told them she was planning to go to Phuket in two days.
According to Thai media reports, Thai police have identified a 32-year-old Chinese man, Ma Qingyan, as a suspect in the case.
Thai police launched a massive search on Friday in the area believed to have been Yang’s last known location and discovered his decomposed body buried in grass on Saturday.
Yang travelled alone to Thailand from Malaysia on June 26, while Ma arrived from Singapore four days later and rented a car, Bangkok-based English-language news site The Nation reported, citing local police.
According to reports, security camera footage from July 1 showed Mr Yang being picked up by Mr Ma that day and the two holding hands, leading Thai police to speculate that the two knew each other.
But that night, Ma was driving alone, stopping at various locations before eventually burning the suitcase near a pond, The Nation reported.
Police speculate that the suitcase may belong to the missing woman, The Nation reported.
The report said Yang was buried about one kilometre from where the suitcase was burned, and that Ma had spent nearly 40 minutes there.
A separate report in the Bangkok Post on Saturday said Yang’s mobile phone signal was last detected in the early hours of July 3 near a park about 70 kilometers (43 miles) from central Bangkok.
The report cited Thai police sources as saying Ma left Bangkok later that day for Hong Kong.
However, between July 4 and 6, Yang’s WeChat Pay account made several purchases in Macau, but there was no record of her leaving Thailand.
It is unclear when Yang’s family received the ransom call, but Thai media reported that they immediately traveled to Thailand.
The incident has sparked public concern in China and led internet users to question whether it is safe to travel to Southeast Asia.
Last month, four Philippine police officers were arrested for kidnapping three Chinese tourists and one Malaysian tourist for ransom.
