Detailed records of the investigation into the so-called Shimoyama Incident of 1949, in which the president of the Japanese National Railways mysteriously died, were recently found by the family of a late JNR official.

Historians say the file, found among the belongings of Takeshi Yamaguchi, an official of the JNR security headquarters who probed the case, may provide some clues to the shady aspects of Japan under the Allied Occupation, which was riddled with mysterious incidents.

But the files themselves seem to shed no new light on the mystery.

Sadanori Shimoyama, the first president of JNR, was found dead on the morning of July 6, 1949, on the tracks of the Joban Line between Ayase and Kitasenju stations in northern Tokyo, apparently run over by a train during the night.

He had been missing since the previous day, when he stopped at the Mitsukoshi department store in Nihonbashi on his way to the JNR office.

Since the incident happened just as JNR was in the process of making large-scale job cuts, speculation circulated about the cause of his death, including that it was suicide brought on by stress. Some said he was killed by leftist radicals, while others pointed to the possibility of Occupation authorities’ involvement.

The investigation went nowhere.

The case was never solved.

Yamaguchi, who died in 1984, was in charge of the JNR probe into the case.

The three-volume file, containing 130 pages of handwritten memos, details the results of his interviews with JNR employees and people connected to places Shimoyama may have been on the day of his death. It also contains the outcome of the official inspection of the scene of his death and other pieces of information provided by the public.

The file was recently found among Yamaguchi’s belongings by his family in Saitama Prefecture.

According to Yamaguchi’s memos, JNR security headquarters, in cooperation with the Tokyo District Public Prosecutor’s Office, conducted its probe on the assumption that Shimoyama had been murdered.

The probe focused on three areas:

JNR employees at the train depot from which the train that apparently hit Shimoyama departed.

People connected with a restaurant that Shimoyama had frequented.

Chemical analysis of spots of unidentified oil found on his clothes.

Yamaguchi questioned 15 JNR workers at the Tabata depot in northern Tokyo but found no inconsistencies in their testimony. Testimony by a worker who said he overheard somebody talking about his involvement in the case later proved less than credible, according to the memos.

The file also indicates there was confusion in the investigation, which also involved the police. Suspicions emerged about a person seen in the restaurant, but the person later turned out to be an investigator from the Metropolitan Police Department.

The probe into the oil spots, which necessitated tracking down oil suppliers to JNR and inspection of storage tanks, proved fruitless.

A memo dated June 26, 1950, quoted a “prosecutors’ theory” that Shimoyama visited the Mitsukoshi store to meet an acquaintance and was later taken somewhere in a car owned by the Soviet Union. But the memo does not provide evidence substantiating the theory.

JNR was broken up into the current Japan Railways group in 1987.

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