The Cau Giay District prosecutors approved Tuesday the police's decision to launch a probe into the actions of 53-year-old Doan Quy Phien.

Phien is a contract driver who drove the bus that picked up and dropped students of the Gateway International School in the district.

On August 6, six-year-old Le Hoang Long was allegedly left behind in a 16-seater school bus for nine hours. He was pronounced dead after being taken to the local hospital in the afternoon.

Long had attended the school for just one day when he died.

A forensic report later revealed that Long died of "heat stroke" and "respiratory failure." He was not suffering from any diseases, the report said.

Police have determined that the death took place in the bus between 12:30-3:30 p.m., and that he suffered no external injury.

The district prosecutors say that Phien was "careless" for not checking the vehicle himself, leaving the task entirely to the bus monitor, 55-year-old Nguyen Bich Quy.

Quy has already been placed under a probe on the same charges. She has been detained while Phien has been granted bail.

Phien works for the Ngan Ha transport firm, which was responsible for transporting students of Gateway to and from the school until August 12, when the school terminated the contract.

The case is still under investigation, with the school's responsibility in the death to be determined later, prosecutors have said.

Questions remain

Before she was arrested for investigation, Quy said Gateway must be held responsible for Long's death before herself or Phien.

She said she did not understand exactly what her responsibilities were as she had neither signed a contract with Gateway nor been instructed on how to receive the students by the school and the transport firm at the time of the incident.

Quy also said she has not had the opportunity to meet up with Phien to clarify several points regarding their responsibilities in the incident.

Long was put on the school bus on Trung Hoa Street, Hanoi's Cau Giay District at around 7 a.m. on August 6. Teachers from the school have said that Long sat on the last row of the 16-seat car, which was carrying 13 students that morning.

At around 8 a.m., Quy and 12 students are believed to have left the bus, leaving Long alone in it. Phien then drove the bus to a parking lot about a kilometer away from the school.

At 3:45 p.m., when the bus was driven back to the school to take the students home, Long was found motionless on the bus floor behind the driver’s seat. The hospital said he was brought in dead.

The temperature in Hanoi that day ranged between 26 and 34 degrees Celsius (79-93 degrees Fahrenheit).