A federal Magistrate Judge has disclosed that key documents in the Al-Arian terrorism case in Florida were improperly shredded by court clerks:

Sami Al-Arian, a former professor at the University of South Florida in Tampa, is in jail on charges of funneling money and support from Chicago and Florida to the radical Palestinian group Islamic Jihad.

U.S. Magistrate Thomas McCoun III said in a letter to Al-Arian's lawyers that search warrants used in 1995 in his case were shredded by mistake, casting doubt on the admissibility of some government evidence.

Investigators used the warrants to raid Al-Arian's home, his university office and a think tank with which he was associated. The absence of the court documents could prevent the U.S. government from using as evidence in court the materials they seized from the 1995 search, Linda Moreno, one of Al-Arian's lawyers, said yesterday.

How could this have happened?

In a letter sent Friday from McCoun, a federal magistrate in Tampa, Fla., to Al-Arian's lawyers, who had requested the court documents, McCoun wrote:

"My deputy reports that these original court files no longer exist. ... Clerks in the Tampa division began shredding magistrate judge files more than five years old. ... This shredding included sealed files kept in the court's vault."

Investigators said "volumes" of documents and other materials had been seized from Al-Arian in 1995. Here's more from Al-Arian's attorney on the import of the document destruction: