Colonel Do Quang Mao, a senior official at the 105 Military Hospital, told VnExpress that Ha, 62, was brought dead to the hospital Thursday morning by staff members of a military detention center in Hanoi's Ba Vi District.

Since the death happened in an area outside the hospital's jurisdiction, the police's forensic team would decide the cause of death, Mao said.

Ha, former chairman of the Joint Stock Commercial Bank for Investment and Development of Vietnam (BIDV), the country's second largest listed bank, was under investigation for "very serious" violations committed during his tenure.

He had worked at BIDV for 35 years until retiring in September 2016. Ha was arrested in November last year.

In its report in June last year, the Central Inspection Committee, the top watchdog of Vietnam's Communist Party, concluded that Ha had violated the democratic centralism principle and working regulations, was guilty of mismanagement, as well as violations of the duties and responsibilities of his position.

Ha violated credit procedures and regulations in approving a number of loans, investments and debt management decisions. In particular, he enabled 12 companies owned by Pham Cong Danh, former chairman of Vietnam Construction Bank (VNCB), to borrow VND4.7 trillion ($206 million) from BIDV.

While BIDV eventually managed to retrieve this money, the loans had helped Danh steal over VND9 trillion from VNCB. At a trial in 2016, Danh was sentenced to 30 years in prison, the maximum jail term allowed by Vietnam's Penal Code.

In addition to holding Ha responsible, inspectors found that the standing committee of BIDV's party unit for the 2010-2015 and 2015-2020 terms had also violated the democratic centralism principle, showed lack of responsibility, poor leadership and lack of inspection and supervision.

These violations in turn enabled multiple systematic violations to occur at BIDV, causing very serious consequences and resulting in many staff members being criminally prosecuted, negatively affecting the lives of all BIDV employees, the inspectors said.

Ha was expelled from Vietnam's Communist Party in June 2018.

During a trial that opened in January regarding violations committed by Danh and Tram Be, a former deputy chairman of Sacombank who also let Danh borrow money from his bank, Ha was summoned as a witness and a person with related interests and obligations.

However Ha did not attend the trial, and his lawyer said he was being treated for cancer in Singapore.

The trial was eventually postponed due to a lack of evidence or a strong enough argument to press charges against Danh, Be and 44 other bankers.

When the trial resumed in July last year, Ha was summoned again, along with 234 other people. He did not show up, as he was reportedly still in Singapore for treatment. Danh was sentenced to 20 years in jail while Be received four years.

The BIDV arrests were part of a nationwide corruption crackdown that has ensnared hundreds of public officials and business people over the past three years.