Iwao Hakamata was born on March 10, 1936, in Yūtō, Shizuoka Prefecture, Japan. He pursued a career in professional boxing from 1959 to 1961, participating in 29 matches with a record of 16 wins, 11 losses, and 2 draws. After retiring from boxing, he worked at a miso manufacturing company in Shizuoka. Hakamata was known for his dedication to work and had no prior criminal record. He lived a modest life and was close to his family, particularly his sister, Hideko.

On June 30, 1966, a fire broke out at the residence of a miso factory executive in Shizuoka Prefecture. The charred remains of the executive, his wife, and their two children were discovered, all bearing multiple stab wounds. Approximately ¥200,000 was reported missing from the home.

Hakamata, an employee at the factory, was arrested in August 1966 after a prolonged and intense interrogation. He confessed to the crimes but later retracted his confession, stating it was coerced through physical abuse and psychological pressure during over 264 hours of interrogation across 23 days. Despite inconsistencies in the evidence, including the discovery of bloodstained clothing that did not fit him and had questionable origins, he was convicted and sentenced to death on September 11, 1968.

Hakamata spent 48 years on death row, the longest in the world, much of it in solitary confinement. In March 2014, the Shizuoka District Court granted a retrial, citing potential evidence fabrication. He was released from prison that month. The retrial began in October 2023, and on September 26, 2024, the court acquitted Hakamata, acknowledging that investigators had likely fabricated evidence and coerced his confession. Prosecutors chose not to appeal, finalizing his acquittal. In March 2025, he was awarded ¥217 million (approximately $1.4 million) in compensation for his wrongful conviction and imprisonment.