A local police chief in Japan on Monday apologized in person to an 88-year-old man who spent nearly half a century on death row before being acquitted in a retrial over a 1966 quadruple murder case.

"I am sorry for the unspeakable burden and trouble we have caused you over the long 58 years from the time of your arrest to your acquittal being finalized," Takayoshi Tsuda, chief of the Shizuoka Prefectural Police, said during a visit to Iwao Hakamata's home in Hamamatsu.

It was the first time that an official of the police or prosecutors has directly apologized to Hakamata, who was arrested by Shizuoka police in 1966 but released in 2014 after new evidence cast doubt on his conviction.

Recognized the same year as the world's longest-serving death row prisoner, he was acquitted in a retrial in September, with the verdict finalized earlier this month when prosecutors decided not to appeal.

His 91-year-old sister Hideko, who was at the meeting, told Tsuda, "Now I think it was fate. At this point, I have no intention of making complaints to the police. Thank you very much for coming all the way here today."

Hakamata has difficulties communicating with others after his mental state deteriorated during his years of incarceration on death row.

Speaking to reporters following the meeting, Tsuda again apologized, saying "coercive and intimidating interrogation" had been used against Hakamata. "We will conduct more thorough and appropriate investigations in the future," he said.

In its Sept 26 ruling acquitting Hakamata, the Shizuoka District Court said investigators had fabricated evidence, including five pieces of clothing Hakamata allegedly wore during the incident. The items played a key role in his conviction.

The court also said his confession during questioning was "forced by inflicting physical and mental pain," calling his interrogation "inhumane."

The ruling was finalized on Oct 9, marking an end to his family's decades-long struggle for justice.

Tsuda's visit to Hakamata came after he had told reporters he intended to offer him an apology in person and that the prefectural police were "sorry that Mr. Hakamata was placed in an unstable legal status for a long time."

His remark followed a similar statement issued by Prosecutor General Naomi Unemoto apologizing to Hakamata.

The former professional boxer was a live-in employee at a miso maker when he was arrested for allegedly killing the firm's senior managing director, his wife and two of their children. They were found dead from stab wounds at their house in Shizuoka Prefecture, which had been burned down.

Indicted for murder, robbery and arson, his death sentence was finalized in 1980.