But the more evidence police obtain, the more doubts they have about the victim's testimony.
The 20-year-old woman was found crying on the balcony of a deserted commercial building in tambon Klang of Muang district early on Feb 15.
She told police she was raped by a gang of men.
According to her account, she and a male friend from the same country drank at a restaurant on the evening of Feb 14.
They decided to continue drinking at another restaurant but were denied entry by guards because they were too drunk.
The woman said her friend decided to go back, leaving her wandering about alone.
She told investigators a pickup truck carrying four men then stopped near the restaurant and the men took her to the commercial building.
Two of the men then raped her, she told police.
But police now say the victim's account is in conflict with that of witnesses and footage obtained from closed-circuit cameras.
Police said the woman came to Nakhon Si Thammarat about two week earlier and applied to work as an English teacher. While waiting for the job reply, she stayed with her male friend in a rental house in Muang district.
On the night of Valentine's Day, she went to a restaurant with her friend.
The restaurant's owners and guards told police the Scot was heavily drunk and intimidated other customers.
She also threw her bag, which contained 6,260 baht in cash, into the restaurant as she was being taken out, police said.
But the key point is what happened to her later that night.
Pol Maj Gen Ronnapong Saikaew, Nakhon Si Thammarat police chief, instructed investigators to work on several key issues.
Following an intense four-day investigation, police were able to obtain surveillance camera footage which showed the woman fell after leaving the restaurant. Two men gave her first aid.
Police identified one of the men as Pongpat Po-soei, a 26-year-old staff member of a car-care shop.
Mr Pongpat was captured not long after. He told police he did not rape the woman but had sex with her by mutual consent after offering her first aid.
Mr Pongpat said he and his friend followed the woman to the second floor of the deserted building and watched as she lay on the floor.
Mr Pongpat told investigators he tried to have sex with the woman but she was too drunk and he did not succeed.
He and his friend then left the spot.
Later he returned and tried to have sex with her again but also failed.
He insisted the woman did not resist while he was trying to have sex with her.
Mr Pongpat said his friend was not involved in the act.
Pol Maj Gen Ronnapong said the police had succeeded in piecing together the timeline of the case through witnesses and footage.
Police are examining semen found in the victim's body to find out whether it matches that of her male friend or the suspect.
Mr Pongpat has been charged with rape after the victim went to police, Pol Maj Gen Ronnapong said. The court will judge the case on the evidence.
The victim, however, did not accuse Mr Pongpat of being the rapist, saying she was unable to recall the incident.
The woman left Thailand on Wednesday.
"The case is not so difficult, but a little complicated because the victim did not give a factual account from the beginning," Pol Maj Gen Ronnapong said. "It is uncertain whether she made it up or was unable to recall it."
The complaint could go to court as a rape case, he said, adding that similar cases occur regularly in the tourist provinces of Phuket and Krabi.
Read the original story on the Bangkok Post here.