"I thought I would die in this room," a woman identified only as Noei said.
Police rescued the woman after entering the apartment in Muang district of Phatthalung province on Wednesday night to arrest Thanadej Kaewchuang.
Her body was bruised, her face was seriously swollen and 10 ribs were broken when commandos from the Crime Suppression Division (CSD) sent her to the ICU at Phatthalung Hospital.
Mr Thanadej, 27, was wanted by police on an arrest warrant issued on Sept 29 for killing and fatally torturing Kamolphet Lamul, 26, in a rented house in Bangkok Noi district of Bangkok on July 21.
Kamolphet's spine and skull were severely damaged when Bang Yi Khan police went to the crime scene that day. Police said she later succumbed to her injuries.
Central Investigation Bureau chief Pol Lt Gen Jirabhop Bhuridej said on Thursday that an investigation revealed Mr Thanadej met the woman on an online dating app, and then persuaded her to move in with him. She was locked in for about one month and beaten until she died. He then went on the run.
The CSD tried to locate the suspect and received a tip-off that he was living with another woman, identified as Ms Noei, in an apartment in Muang district of Phatthalung.
Ms Noei, who lived in Lamphun, told police that she met Mr Thanadej on a dating app in early August. One month later, she decided to take a train to the southern province after he told her that he was falling in love with her and wanted to meet up.
Mr Thanadej picked her up at Phatthalung train station for breakfast. He then took her to his apartment and went on a jealous tirade, accusing her of looking at another man during the meal.
Ms Noei said she was locked in the room for more than a month and was continually beaten until the police showed up.
"When he took meth pills, he attacked me more," she said. "I was suffering in the room." She gave the police a wai for saving her life.
Urine tests carried out after the arrest showed Mr Thanadej had taken drugs.
Pol Lt Gen Jirabhop said the man had confessed both to the murder charges in Bangkok and attacking Ms Noei in Phatthalung.
Mr Thiradej claimed he had not acted intentionally, but was unable to control his emotions because he was jealous, according to the officer.
Pol Lt Gen Jirabhop believed there may be more female victims given his pattern of using online dating to meet women and then torture them.
The suspect was released from jail in January last year after serving a jail term for drug charges, according to police records.
Ms Noei filed an assault charge against him at the Muang police station in Phatthalung, while the suspect was sent to Bangkok. The Bang Yi Khan police station pressed murder charges on Kamolpeth on Thursday.
