TOKYO (Kyodo) -- Tsutomu Hotta, a former Japanese prosecutor known for his role in the investigation of the Lockheed bribery scandal and prosecution of the late Prime Minister Kakuei Tanaka in 1976, died of old age on Nov. 24, a law firm and social work organization he founded said Wednesday. He was 90.

Hotta, a graduate of Kyoto University, became a prosecutor in 1961. As a member of the Tokyo prosecutors office's special investigation squad, he played a key role in the conviction of Tanaka for taking bribes to influence a domestic airline to purchase Lockheed aircraft.

After retiring in 1991, he turned to the field of social welfare services. He died at his home in Kanagawa Prefecture.