A Thai woman claims she discovered her Finnish boyfriend dead with his throat cut and the knife placed on his chest while he was lying on their bed.

Aranya Srisaengdam, 50, allegedly found her lover Markku Tapani Karjalainen, 57, lifeless at their house in the notorious coastal region of Chonburi on Tuesday, February 28.

Police Lieutenant Colonel Paiboon Laohanawat from Sattahip Police Station received a report at 8:30 AM and went to the single-storey house in Bang Saray district to investigate.

Officers found the Finnish man, from Kajaani, wearing black shorts on his bed and a knife was laid on top his chest. His windpipe had been severed from the cut and his chest was covered in blood.

Aranya said that her boyfriend Markku had woken up at 6 am yesterday, and that she had prepared breakfast for him before leaving to accompany a relative to school. When she came home, she reportedly found him already dead.

She told cops they had been together for five years in Thailand, but their tribal marriage ceremony was not legally registered. Markku allegedly went back home to Finland for two years, before returning to Thailand nine months ago and paying for a house in his girlfriend's name.

Aranya further claimed that her husband was stressed over calls from Finnish police saying he was being impersonated as a money lender.

Police Lieutenant Colonel Paiboon Laohanawat of the Sattahip Police Station said no traces of a struggle were found in the room.

However, the couple's neighbours told police that they often heard the two arguing with each other.

The police chief said: 'Officers are now questioning Aranya further at the police station. We are checking the house extensively to identify if there are any suspects.'

Markku's body has been sent to the Institute of Forensic Medicine for a post-mortem examination. Police are coordinating with the Finnish Embassy to inform his relatives of his death.