A Japanese man who held the record for the longest time spent on death row was acquitted of murder on Thursday, according to his legal team, bringing an end to his family's long quest for justice after a wrongful conviction for crimes committed nearly 60 years ago.

The Shizuoka district court exonerated Iwao Hakamada, 88, in a retrial of the murders of four people in the central Japanese region in 1966. Hearing the words 'not guilty' in the courtroom was a moment of profound relief for Hideko Hakamada, who has fought tirelessly to clear her younger brother's name for decades.

'When I heard that, I was so moved and happy, I couldn't stop crying,' she said during a televised briefing. Hakamada spent 45 years on death row before a court ordered his release and a retrial in 2014 due to doubts about the evidence used to convict him. The former boxer, who has lived with his sister since his release, was accused of stabbing his former boss and family to death before setting their home on fire.

Although he briefly confessed to the crimes, he later retracted his confession and maintained his innocence throughout his trial. Despite this, he was sentenced to death in 1968, a penalty that was upheld by Japan's Supreme Court in 1980. Norimichi Kumamoto, one of the Shizuoka court's three judges who had originally sentenced Hakamada to death, petitioned the Supreme Court for a retrial in 2008, but his request was denied.

Hakamada's lawyers argued that DNA tests on bloodstained clothing allegedly belonging to their client showed that the blood was not his. Human rights group Amnesty International celebrated the exoneration as a 'pivotal moment for justice' and called on Japan to abolish the death penalty.

'After enduring almost half a century of wrongful imprisonment and a further 10 years waiting for his retrial, this verdict is an important recognition of the profound injustice he endured for most of his life,' Amnesty said in a statement. 'It ends an inspiring fight to clear his name,' the group added.

The government's top spokesperson, Chief Cabinet Secretary Yoshimasa Hayashi, declined to comment on individual cases but acknowledged the Shizuoka court's ruling.