MIRAMAR, Fla. -- The FBI has arrested a man in Memphis, Tenn. in connection with the envelopes containing a white powder mailed to 22 Broward County mayors.

The suspect, Dane Swendel, 46, (pictured, left) is also linked to several threatening letters that were sent to Broward County Schools several months ago.

Officials say the latest incident was a hoax, but they are taking it very seriously.

On Thursday, the FBI descended upon 10 Broward County city halls after letters containing a suspicious white powder turned up.

On Friday, another 12 mayors in Broward County received envelopes also containing a white powder. That brings to 22 the number of such envelopes sent to Broward officials.

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Fire officials, police officers and hazardous materials crews rushed to Sea Ranch Lakes City Hall around 3 p.m. Thursday when the first envelope was found.

Next, the mayor in Tamarac discovered and opened a similar letter containing white powder. The mayor and two workers were exposed. They immediately removed their clothes and took showers just to be safe.

The same kind of letters popped up in eight other city halls throughout the afternoon.

Preliminary tests showed that the powder was not anthrax, ricin or any dangerous substance. Officials now say the powder is corn flour.

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Letters Found With White Powder

No injuries were reported by the Broward cities, but one Sea Ranch Lakes employee felt slightly ill and was taken to the hospital as a precaution, officials said.

All of the letters had Memphis, Tenn., postmarks and were addressed to either the mayor or city manager of each city.

Broward officials worked with the FBI to find the sender, said Sheriff Ken Jenne.

"It's not funny. We take this very serious," Jenne said. "I think when you see white powder and South Florida, some alarms go off."

A worker at Boca Raton's American Media building died after being exposed to anthrax in an envelope mailed to the building in October 2001. The tabloid newspaper publisher moved from the building, which wasn't declared decontaminated until this summer.