The failure of a team of experts to find DNA on bloodstained garments has dashed hopes for the retrial of a man sentenced to death for a 1966 quadruple murder.

The experts said Thursday they were unable to detect DNA on the clothes reportedly worn by Iwao Hakamada, 64, when he allegedly killed four people in 1966.

Supporters of a retrial had hoped that the DNA test would prove their theory that the garments had been planted by police as false evidence.

Hakamada, a former sixth-ranked Japanese featherweight professional boxer, has been on death row since 1968.

He was arrested on suspicion of murdering the director of a soybean paste maker in Shimizu, Shizuoka Prefecture, and three of the man's family members. The victims were also robbed and their house was set on fire.

The results of the DNA test have been sent to the Tokyo High Court, including a statement by experts indicating they could not detect any human DNA.

One of Hakamada's defense lawyers said, "Because 34 years have passed since the event, the bloodstains were too old and no DNA could be detected."

While the blood-soaked garments played a decisive role in the indictment of Hakamada, his lawyers have argued that the evidence had been fabricated by police.

The garments, found about a year and two months after the murders took place in June 1966, are too small to fit Hakamada, they said.

Although Hakamada had confessed to the crimes, he later pleaded innocent in court, claiming he made the confession under duress.

In August 1967, police found blood-soaked clothes, including a shirt, pants and underwear, in one of the company's soybean paste tanks.

Police said they had detected on them the blood types of all the victims. But the defense team, doubtful of the authenticity of the evidence, in 1997 called for a DNA test on the garments to examine whether the blood really came from the victims.

The Shizuoka District Court sentenced Hakamada to death in September 1968. Hakamada appealed the sentence to a higher court, but the Tokyo High Court turned it down in May 1976, and the Supreme Court upheld that ruling in November 1980.

The Japan Federation of Bar Associations started working for Hakamada's vindication in 1982, saying the case reeks of false charges.