Russian authorities are still searching for Uthai Wenbap, a 36-year-old Thai cook who went missing in Russia while returning to Bangkok from working in Budapest, the Thai embassy in Moscow said on Sunday.
The man missed the connecting flight on June 15 and then vanished in Moscow three days later.
The disappearance of Mr Uthai came to light after Prapudson Promcharroen, his wife's sister, posted on June 21 that his family could not contact him and sought help from the public.
"He was expected to arrive in Bangkok on June 16. When we contacted the Immigration Bureau, we were informed that Mr Uthai did not return to Thailand," she told the Bangkok Post.
According to Mr Uthai's Aeroflot itinerary, he left Budapest on June 15, had a two-hour layover to change planes at Moscow's Sheremetyevo International Airport, and was due to arrive in Bangkok on June 16, Ms Prapudson said.
After Ms Prapudson made known the disappearance of her brother-in-law, a Russian coffee shop employee at the airport contacted her because he saw Mr Uthai on June 17. However, police told the embassy that it happened on June 18.
"My brother-in-law tried to enter the shop drunk, so the staff decided to notify police," she said.
In CCTV footage, Mr Uthai appears intoxicated and is half-naked. The man from Nong Khai province had tied a black shirt around his head and walked in barefoot. He also pushed aside seating and caused a din.
Pawinrat Mahaguna, the first secretary of the Thai embassy in Moscow, indicated that police detained Mr Uthai on the night of June 18 because he was drunk. However, they released him the next day when he had sobered up.
"Police discharged him on June 19 because he had done nothing wrong. Then he disappeared. He was caught on CCTV leaving the airport and taking a bus to Khimki, a city close to Moscow. We have asked the Russian authorities to track him," she told the Bangkok Post.
"We contacted the Russian Ministry of Defence and check with the Bureau of Accidents Registration every day to see if any Thais in Russia have died or entered hospital.
"Liza Alert, a search and rescue volunteer group, is helping us look for the missing man," she said.
"We have also asked local media to publish his story to boost our chances of finding him," the Thai diplomat said.