MIAMI -- A senior law enforcement official says the scientist detained at Miami International Airport because of a suspicious item in his luggage had once been charged with illegally transporting bubonic plague.

The official told The Associated Press on Friday that no dangerous material was found on 70-year-old Thomas Butler after he was detained Thursday night. He was released Friday.

The official said Butler cooperated fully after he arrived on a flight from the Middle East. The official requested anonymity because he wasn't authorized to release the information.

Butler was teaching at Texas Tech in 2003 when he was accused of illegally transporting the deadly germ. He was acquitted on those counts but convicted of fraud. He served a two-year sentence.

He was "very cooperative," FBI agent Michael Leverock said at a news conference in Miami.

The metal canister that sparked concern was a legitimate experiment, said another government official who also requested anonymity to discuss the ongoing investigation.

That official said the man has a prior arrest record related to biological material and is a professor at Ross University in Dominica on a teaching assignment in Saudi Arabia. The professor told law enforcement that the metal canister was used for medical testing, and the FBI found that it was used to transport dead bacteria samples, the official said.

Most of the airport was shut down Thursday night after officials found the canister in the scientist's bag. A Homeland Security spokesman said at first it looked like a pipe bomb, but no explosives were found.

A police bomb squad spent hours scouring the airport and passengers had to be evacuated from four of the airport's six concourses and airport roadways were closed down, police and airport officials said. They described the shutdown of the concourses as a public safety precaution.

The airport fully reopened just after 4 a.m. Friday before the first scheduled morning departures.
"Everything's back to normal," airport spokesman Greg Chin told The Associated Press.

Passengers, workers and others were allowed back in just as the airport was expecting the first of 1,500 passengers on flights between 4 a.m. and 6 a.m. alone -- and more thereafter.

The Miami International Airport Hotel, which is located near the airport's international terminal, was also evacuated, Chin said.

The Transportation Security Administration declined to identify the passenger, saying in a terse statement that the screener spotted something suspicious in a checked back at about 9 p.m. Thursday.

Chin said between 100 and 200 passengers were evacuated initially.

"I'm still not sure how many flights came in during this time, but any that did were relocated to the eastern or western ends of the airport," Chin said, adding parts of Concourses D and J remained open to flights while the evacuation order was in effect for remaining areas.

Lennox Lewis, was waiting to fly to Barbados later Friday morning in one of the four concourses that had been closed. He said the Miami airport is "one of the most stringent" to get through because he has to be fingerprinted and have his picture taken at customs.

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THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

MIAMI (AP) — A scientist has been detained at the Miami International Airport after screeners spotted a metal canister in his luggage that looked like a pipe bomb, prompting an evacuation, a government official said.

The FBI and Miami-Dade police were interviewing the 70-year-old man, the official said Friday. No explosives have been found. The official spoke on condition of anonymity to discuss the ongoing investigation.

The man being questioned at the airport is an American citizen, FBI agent Michael Leverock said at a news conference in Miami.

"He's being very cooperative," Leverock said. "He's not under arrest at this time."

Leverock said the man was on a flight that flew into Miami but would not say where he flew from.

The item found in the man's luggage has been brought to a lab for more testing, Leverock said.

"We don't know if a crime has been committed here," he said.

Although law enforcement officials found no explosives, the item was being tested for contaminants, Homeland Security spokesman Nicholas Kimball said.

A police bomb squad spent hours scouring the airport and passengers had to be evacuated from four of the airport's six concourses Thursday night and airport roadways were closed down, police and airport officials said. They described the shutdown of the concourses as a public safety precaution.

The airport fully reopened just after 4 a.m. Friday before the first scheduled morning departures, which signaled the start of the peak Labor Day weekend.

"Everything's back to normal," airport spokesman Greg Chin told The Associated Press soon after the closed concourses reopened.

He said the end of the evacuation order largely coincided with the nighttime drop-off in flights. Passengers, workers and others were allowed back in just as the airport was expecting the first of 1,500 passengers on flights between 4 a.m. and 6 a.m. alone — and more thereafter.

The Miami International Airport Hotel, which is located near the airport's international terminal, was also evacuated, Chin said.

The Transportation Security Administration declined to identify the passenger, saying in a terse statement that the screener spotted something suspicious in a checked back at about 9 p.m. Thursday.

The federal agency responsible for air travel security said four of the six concourses in the 2-mile long complex — Terminals E, F, G, and H — had been evacuated beginning late Thursday.

Miami-Dade Police said a bomb squad spent hours at the airport with fire officials and the others. Fire trucks and police vehicles stood by and a hazardous material team was spotted at the scene.

Police spokesman Alvaro Zableta had urged those with scheduled departures Friday to check with local air carriers.

Chin said between 100 and 200 passengers were evacuated initially.

"I'm still not sure how many flights came in during this time, but any that did were relocated to the eastern or western ends of the airport," Chin said, adding parts of Concourses D and J remained open to flights while the evacuation order was in effect for remaining areas.

Lennox Lewis, was waiting to fly to Barbados later Friday morning in one of the four concourses that had been closed.

He said the Miami airport is "one of the most stringent" to get through because he has to be fingerprinted and have his picture taken at customs.

"Traveling right now is a pain but you have to do it. I don't get overly worried that people will do stupid things," said 39-year-old Lewis, who was flying with his two small children after a trip to North Carolina and Disney World.

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Associated Press photographer Alan Diaz in Miami and Associated Press writers Eileen Sullivan in Washington and Bill Cormier in Atlanta contributed to this report.