DEARBORN, Mich. -- The Local 4 Defenders Terrorism Task Force has learned more about one man's visit to a library in Ohio where he did research on water systems.

FBI agents have also recently been to the Henry Ford Library in Dearborn.

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The Defenders ask the question: Did some local men who were recently arrested with fake visas and documentation -- and who may have been tied to a terrorist plot -- visit the Dearborn library for research?

The investigation centers around water treatment plants, maps of cities, and why Ahmed Hannan and Karim Koubriti would be interested in such information.

The two Detroit men were recently indicted on charges of possessing false documents and visas, and are under questioning on their possible ties to terrorist organizations.

Reports out of Canton, Ohio, put an unknown associate of the men at a library there doing research on the city's water system. The man also reportedly asked for books on parasites and diseases that can be passed from animals to people.

Local 4 Defenders have learned that the FBI was at the Dearborn library recently asking questions. A library spokesperson told Local 4 that FBI agents interviewed library employees.

The FBI will not say if Koubriti or Hannan walked the Henry Ford Library aisles to do research on local water systems and to study diseases since it is an ongoing investigation.