Police are seeking help from the US Federal Bureau of Investigation (FBI) to help identify a dismembered body found in a freezer during last week's raid on a passport forgery gang.
Tourist Police Division chief Surachet Hakpal said Thai authorities had asked the FBI to provide files of fingerprints. However, fingerprints collected from the frozen body were too unclear to find a match as the body had been frozen for months.
He said the FBI will help police check the identity from dental records instead.
Maj Gen Surachet said police will search a house Monday in Soi Onnuj 1 where one of the suspects stayed.
Metropolitan Police Bureau chief Sanit Mahathavorn said investigators will meet forensic experts and representatives from the US embassy Monday to discuss the identification verification process of the dismembered body and the findings of forensic tests.
The body of a foreign male, chopped up into six pieces, was found on Friday when police raided a five-storey building in Sukhumvit soi 56 following a tip-off that the premises were being used by a passport forgery gang.
Three foreign nationals were arrested in the raid and charged with multiple offences including resisting arrest, illegal possession of firearms and ammunition, forging official documents and concealing a corpse.
As authorities were verifying their travel documents, two were identified from passports as Americans James Douglas Eger, 66, and Aaron Thomas Gabel, 33. The other was identified as British national Peter Andrew Colter, 56.
"What police need to know is the identity of the dead person. Who was he? Where was he from? How was he involved with Mr Colter?" he said.
Pol Lt Gen Sanit said some techniques were employed but were not good enough to identify the victim at this stage and the fact the body had been frozen for months made forensic work more difficult.
However, he insisted an autopsy would be able to tell what caused the death and when he died. It is hoped initial findings, which are expected Monday, will help police solve the case.
The commissioner said police have some pieces of useful information which need to be verified before they can release them publicly.
He said police believe the freezer is a second-hand product and they are preparing to search the house from where the freezer was moved.
Mr Colter was quoted as telling police the freezer belonged to a friend who had died of cancer and he did not know what was inside it.
He said the freezer was moved to the building four months ago. Police later found the key to the freezer in Mr Colter's bedroom.
Pol Lt Gen Sanit said police questioned 10 people including a woman who was romantically involved with Mr Colter and they are reviewing footage from security cameras to identify potential witnesses.
Pol Lt Gen Sanit said Mr Colter, who has been in Thailand for five years, is involved in a passport forgery racket and it is believed he has no authentic identification documents.
The house rental contract made in August last year is signed by Mr Eger while some of the chemical substances seized from the house are restricted goods and believed to be used in passport forgery.
Central Investigation Bureau chief Thitirat Nongharnpitak said police have reviewed the suspects' phones and found their potential witnesses and suspects.
He said the three suspects provided little cooperation to investigators and police are waiting for information from the US authorities and Interpol.
Pol Lt Gen Natthon Phroasunthon, commissioner of the Immigration Bureau, said authorities are working to verify the identity of the suspects who have multiple passports with different names and nationalities.
He said no passports were sent to the bureau for examination, noting the immigration authorities would be able to quickly verify if they are genuine or forged.
He said it is likely the passports used by the men in house rental deals or car purchases are fake.