The weekly magazine Stern and the first German public television channel ARD, in reports to be published and aired on Thursday, focus on Marwan Alshehhi, who piloted the Boeing plane which crashed into the south tower of the World Trade Centre.
How Alshehhi then managed to slip from the view of the CIA is the focus of the reports by ARD and Stern, details of which were provided to Deutsche Presse-Agentur in advance on Wednesday.
The joint investigative reports said that in January 1999, Germany's security agency BfV first noted the name of a man named "Marwan" after he had placed calls with Haydar Sammar, a German- Syrian living in Hamburg, who had been under surveillance since 1993.
Two months later, in March 1999, the BfV passed the information about Marwan on to the CIA, which then also began keeping surveillance on him, ARD and Stern reported.
The reports said the CIA had detailed information about Marwan Alshehhi, and the fact that he was from the United Arab Emirates and studying in Germany.
The CIA had his cellphone number and knew that he was in contact with Haydar, whom the Americans had suspected of being al-Qaeda's contact man in Germany.
The reports add to the growing evidence of mistakes made at the CIA and other security agencies in the United States in failing to detect the plot by the suicide plane hijackers. - Sapa-DPA