Justice Minister Mayumi Moriyama said Friday her ministry will reopen the case of a 49-year-old male prisoner who died under dubious circumstances in 1995 after being placed in a leather restraint at a juvenile prison in Kawagoe, Saitama Prefecture.

"I have been informed roughly (of the circumstances surrounding the man's death), and we will examine the case closely," Moriyama told a news conference following the day's Cabinet meeting.

According to Justice Ministry files disclosed this week, the man was arrested in October 1995 for allegedly murdering his mother.

The man reportedly acted violently following his detention at Kawagoe Juvenile Prison and was moved to a protective chamber.

On the third day of his detention, guards placed him in the leather restraint after he allegedly attacked prison staff after breakfast time, the files show.

The man suddenly fell ill after the incident and was transferred to a nearby university hospital. Two hours later, his heart and lungs stopped functioning.

Au autopsy found that the man had suffocated on his own vomit.

An investigation was opened, but the Saitama District Public Prosecutor's Office, which was then known as the Urawa Public Prosecutor's Office, eventually opted not to open a criminal case over the death.

Hideharu Arimitsu, head of general affairs at Kawagoe Juvenile Prison, said the death will be re-investigated, although he emphasized that he believes the case was "properly handled" by the prison at the time.

There is also a discrepancy over the time of death. While records compiled by a university doctor who examined the body says the man died at 8:05 a.m. Oct. 31, 1995, the death record kept by the prison claims he died nearly three hours later, at 11 a.m.