Yahoo chief executive Scott Thompson told top Yahoo employees on Thursday that the false degree in computer science that has been listed in his biography for years was put there by a placement firm, according to news reports.

The embattled CEO, who has been under fire since a Yahoo investor revealed the false academic credential last week, also said that he had never proofread the résumé compiled by the firm and did not know of the error until the uproar began, a report from Reuters said. The report was based on comments from unnamed Yahoo employees.

Thompson said that he never submitted a physical résumé to either Yahoo or PayPal, where was president of its eBay division before joining Yahoo in January, because hiring firms compiled their own dossiers to give to prospective employers. According to a report Thursday from Business Insider that also relied on unnamed Yahoo employees, Thompson said he did not review the documents from the firms. It’s likely, he said, that a misstated credential listed on a dossier by a placement firm employee was duplicated repeatedly in later biographies.

Thompson said that he made a mistake by not reviewing the documents, the report said.

Yahoo declined to comment on the report; the Web giant’s board of directors is investigating the matter. On Wednesday, the board member who led the search committee that hired Thompson, Patti Hart, announced she would not seek reelection to the panel.

Since first calling attention to Thompson’s false biography, activist Yahoo investor Daniel Loeb has repeatedly demanded that the company to fire the chief executive. Loeb has been waging a proxy fight against the company and campaigning to have nominees from his hedge fund, Third Point, placed on the board. He has called on the company to appoint an interim CEO immediately.

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Post Leadership: Yahoo CEO Scott Thompson’s incorrect resume raises questions for tech company’s board