The ministry plans to tell the Diet as soon as Monday that it has found several instances where content present in the original versions of the documents was removed later, the sources said.
A Finance Ministry official linked to a scandal involving the wife of Japan's prime minister has been found dead, the ministry confirmed Friday, and a second official resigned. He had come under fire for allegedly making false remarks about the sale to the Diet a year ago in his previous role.
The employee worked in the department of the ministry managing state-owned assets, according to Jiji.
The original document described the land transaction between the ministry and the school operator as "exceptional", but this word was missing in the version made available to Diet members during debate about the scandal a year ago. The emergence of a voice recording cast doubt on Sagawa's claim.
The revelation of the male official's suicide comes at a time when opposition parties are stepping up their offensive against the government after The Asahi Shimbun alleged March 2 that relevant Finance Ministry documents have been doctored.
Protests were recently held in front of the National Tax Agency building and in other places to demand Sagawa's resignation.
But it is unclear whether the official's death is related to the dubious transaction.
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Tillerson's schedule for Saturday also included a site visit to PEPFAR, a U.S. program that works to fight AIDS in the continent. It is believed that the 2019 general elections will also be part of discussions between Tillerson and President Buhari.
Chief Cabinet Secretary Yoshihide Suga and Aso, respectively, admitted they heard that the official had died, without elaborating further.
The official belonged to a department in charge of the land transaction in February a year ago, when the issue first came to light. But the Board of Audit of Japan said in November the discount happened because the price was not properly calculated.
Abe indicated the results of an internal investigation by the ministry will be released early next week.
The sale has erupted into a scandal that has dogged Abe since it first emerged last February, though the prime minister has denied any wrongdoing and his approval ratings remain solid.
Abe's wife Akie had been named honorary principal of the planned school, but she stepped down amid public scrutiny after the details of the sale were revealed.
Kagoike and his wife Junko have been indicted on unrelated subsidy fraud charges.