Claas Relotius, who was once named CNN Journalist of the Year, resigned from his job as a writer and editor at German news magazine Der Spiegel after confessing to purveying fake news on a "grand scale".
Relotius, 33, who joined the publication as a freelancer in 2011, has admitted deceiving readers in some 14 stories published in the magazine.
The article's co-author, Juan Moreno, grew suspicious and collected evidence against Relotius during a subsequent trip to America on another story.
The reporter contributed around 60 articles to Der Spiegel, one of the leading German magazines for investigative reporting.
Moreno reportedly informed the magazine's administration and conducted an investigation of his own into the article the two were reporting on.
"The management of Der Spiegel will appoint a committee of internal and external experts", the publication said, adding that the results will be published. It also called on readers to contact them with any information on the matter.
In his confession to his employer, he said: "It wasn't because of the next big thing".
The reporter also wrote for a string of other well-known outlets, including German newspapers taz, Welt and the Frankfurter Allgemeine's Sunday edition.More news: Share of women in global workforce, politics falls: WEF report
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"My pressure to not be able to fail got ever bigger the more successful I became".
Among them, "The Last Witness", about an American who allegedly travels to an execution as a witness, "Lion Children", about two Iraqi children who have been kidnapped and reeducated by the Islamic State, and "Number 440", a feature about alleged prisoners at the U.S. detention facility in Guantanamo Bay, Cuba.
What Relotius produced were "endless pages of an insulting, if not hilarious, excuse for journalism", according to investigators.
Earlier this month, he won Germany's Reporterpreis (Reporter of the Year) for his story about a young Syrian boy, which the jurors praised for its "lightness, poetry and relevance".
That's especially true for Spiegel reporter Relotius who mostly wrote about people living overseas and without access to the German magazine. The publication said the issue "marks a low point in the 70-year history of Der Spiegel".
The magazine said Relotius's senior editors confronted him after a fellow journalist at the magazine voiced suspicions.
But at a time when political parties are deeply polarised on both sides of the Atlantic, the Spiegel controversy could also bolster those who now regularly portray reporting as "fake news". "In particular, it said, in the department, "Society" in which he worked "(his) colleagues are astounded and sad...the affair feels like a death in the family".