TOKYO — Japan on Friday offered a public apology to a Nepalese man who spent 15 years in jail for a murder he did not commit.

Justice Minister Makoto Taki told a press conference he was sorry that Govinda Prasad Mainali had spent so long in prison for the 1997 murder of a businesswoman-turned prostitute in Tokyo.

"I deeply apologise for his long detention period of 15 years," said Taki, according to Kyodo News.

Mainali, 46, was declared not guilty by the Tokyo High Court in a retrial that ended this week.

The same court had in 2000 found him guilty of killing the 39-year-old woman and sentenced him to life in prison, overturning a lower court's verdict of not guilty.

Mainali told reporters in his native Nepal, where he was sent by immigration authorities in June after his conviction was quashed, that Japan's justice system had let him down because it had overlooked crucial evidence.

That included the DNA testing of semen left inside the dead woman and of biological samples taken from under her fingernails.

"I was forced to undergo 15 years of horrible and torturous time in jail despite being innocent," he said. "Had the DNA test not been conducted, I would have been languishing in jail and probably would have died there."

The case has led to media questioning of Japan's justice system and particularly the work of prosecutors, who take a leading role in criminal investigations.

Japan has a very high rate of convictions and relies heavily on confessions. Suspects can be held for many weeks without being charged while police make their case.

Critics say this leads to abuses where those arrested are ground down until they give investigators what they want.

No one else has been arrested in connection with the murder.