FBI Probing University Bomb Threats

(CBS) -- The FBI is investigating a series of bomb threats made against at least 13 universities and colleges over the past 10 days - apparently timed to coincide with the start of the new school year, reports CBS News correspondent Bob Orr.

The threats, received in the form of anonymous e-mails, all appear to be hoaxes. A number of evacuations have taken place, but no explosive devices have been found, Orr reports.

Clemson University in South Carolina has received three bomb threats and the following have received at least one: University of Akron, University of Alaska/Anchorage, Carnegie Mellon, Cornell, Iowa, MIT, Middle Tennessee State, University of New Hampshire, Oregon State, Princeton, Western Illinois, and William & Mary.

Federal investigators suspect many of threats were pranks, possibly sent in by students seeking to disrupt the start of classes. Nevertheless, the FBI and Department of Homeland Security are investigating, Orr reports.

There is nothing at this point to link the threats to any one person or group, but that possibility has not been ruled out. Investigators say there is no reason to believe the university bomb threats have any connection to the expanding series of bomb threats and extortion attempts made against Wal-Marts, banks and other stores around the country.

The threats and extortion attempts against U.S. stores, banks, and businesses continue with more threats being called in nearly every day, according to U.S. officials. By last count, at least 24 threats have been received by businesses in more than 17 states, Orr reports.

The FBI tells CBS News it is investigating a possible link between the threats and a bank robbery that occurred in March in Miami Beach, Fla.

One suspect was arrested at the bank, but a second suspect, who took part in the robbery by cell phone, remains at large, Orr reports. Law enforcement officials have identified that second suspect (the cell phone accomplice) as 27-year-old Allan Sharif, who they believe was calling from Portugal.

Sharif is a fugitive, indicted in New York in 2005 on wire fraud charges. The U.S. Secret Service has a warrant for his arrest.

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The Associated Press and CBS News contributed to this report.