In February this year, 41-year-old Eng Yong Kit forced his 24-year-old Vietnamese girlfriend into a hotel room in Ho Chi Minh City.
With himself and the woman inside, Eng then then locked the room and used a bed to it to prevent others from rescuing her.
Local police, together with representatives of the Singaporean Consulate General in Ho Chi Minh City went to the hotel but failed to talk him into opening the door.
Eight hours later, police broke down the door and hurled smoke grenades in their bid to rescue the trapped woman.
Eng was arrested and detained.
Eng said he met his girlfriend, who is believed to be a sex worker, online.
He said they started dating in June last year, but she later asked to break up with him, which prompted him to act out.
Eng has since been released, since he had been detained since February.