The Tokyo High Court said Monday it will stop hearing an appeal by prosecutors against the acquittal of Takeshi Abe on charges of negligence resulting in a patient's death, saying the 87-year-old HIV expert has become mentally incompetent.

A psychiatric examination by a court-commissioned doctor determined that Abe "does not have the ability to discern good from bad," his lawyer said Feb. 10.

Prosecutors were appealing a March 2001 Tokyo District Court acquittal of Abe on charges of professional negligence resulting in the AIDS-related death of a hemophiliac.

The lower court ruled the 1991 death was not foreseeable when Abe administered HIV-tainted blood products to him in 1985.

Abe ordered a subordinate to administer unheated blood-clotting agents to the patient on three occasions in May and June 1985 when Abe headed the No. 1 internal medicine department at Teikyo University's hospital. Abe later became the university's vice president.

The defense counsel had asked the court to halt the trial based on the mental test.

The Code of Criminal Procedures requires courts to halt a trial when a defendant is deemed mentally incompetent.

The lawyer said Abe was hospitalized several times last year for treatment of chronic heart illness and has stopped responding to his lawyers.

In the 1980s, some 1,431 hemophilia patients in Japan contracted HIV from tainted blood products, according to a 2001 survey by the Health, Labor and Welfare Ministry.