Ho Chi Minh City police on Monday expanded an investigation into the death of a wealthy businessman who was tied up and robbed last week.
Police said they have arrested six suspects, including Phan Thi Ngoc Diem, who they said was the mastermind.
Diem, 25, befriended the 43-year-old victim, Nguyen Van Tho, and learnt that he was a wealthy businessman, according to the police.
Initial investigation found that on October 21, she lured him to a rented house in District 12. When he entered the house, there were five men waiting.
Police said the gang then tied him up, put rags into his mouth and covered his eyes, mouth and nose with duct tape.
They then took his mobile phones, and VND160,000 ($7.2) in cash.
The gang then fled the scene in the victim's car, which they later left on a road in Tan Binh District.
Tho's body was discovered at around 6 p.m. the same day. Police said he had been choked to death.
Police arrested three of the suspects in the An Giang Province on Friday morning and two others in Vinh Long Province in the evening.
Diem was arrested the next day in Ho Chi Minh City, police said.
Police said the gang had just rented the house one day before the crime.