A Canadian man has been questioned after his Thai girlfriend was found hanged in her nail salon.

Randy Frederick, 51, was interviewed by the Phuket Immigration Bureau at the Phuket International Airport before he was due to board a flight to Singapore on February 13.

He was questioned over the death of his lover Wanwisa Riwklang, 31, who was found dead at her nail salon in Phuket on February 8.

Wanwisa's brother Kriangsak raised his concerns with the police, saying his sister had two children and a sick father to take care of.

Kriangsak said Wanwisa and Randy had met at an 'entertainment venue' owned by the Canadian around four to five months ago. Within that short span, they fell in love and were engaged.

Randy had also opened the nail salon for Wanwisa, who said she felt uncomfortable working at the 'entertainment venue'.

Kriangsak met with Deputy National Police Chief General Surachate Hakparn to discuss the case.

The high-profile officer said: 'The Canadian man has been placed on a watchlist, but there is not sufficient evidence to connect him with the death of his girlfriend.

'We have contacted the Immigration Department to request that the suspect be detained if he tries to leave since we still need to investigate the case.'

Cops said they are awaiting drug test and autopsy results, and have not filed any charges against Randy.