The family's 22-year-old son had been taking flying lessons, acquaintances said.
Both the terrorist attacks on the World Trade Center and Pentagon, and a spate of deadly anthrax mailings, had significant South Florida connections. But a federal law enforcement official in Washington said the search in the suburbs of West Palm Beach was unrelated to those ongoing investigations.
The official said authorities were probing a possible connection between a family member and a local flight school, but gave no additional details.
Local FBI spokeswoman Judy Orihuela said the investigation of the house in Greenacres would probably be finished Wednesday, but she declined to disclose what agents were looking for or why they had targeted the residence.
"It's a sealed federal search warrant, so there is not much more that I can say," she said.
According to property records, the single-family home in the gated community of Fairway Isles is owned by Mohammed and Afaf Almasri. The records show Mohammed Almasri bought the house on June 30, 2000. He told people he was an engineer.
Some neighbors said that on Sept. 9, 2001, two days before terrorists hijacked four airliners, a white minivan pulled into the driveway, and the family loaded it with suitcases and quickly departed.
"We were wondering why they were rushing. It was so not in keeping with their normal behavior," said Kristina Daddio, a neighbor. "These people are very pristine and proper."
According to neighbors, the family's son, Turki, had been taking flying lessons. Shortly after the Sept. 11 attacks, and revelations that at least 15 of the 19 young Muslim hijackers had lived in Florida, and some received flight training here, Greenacres residents called the FBI to report the Almasris' abrupt departure.
Orihuela declined to say whether the FBI had found anything suspicious during the two-day search. Agents scanned the yard with metal detectors, dug up flower beds and removed a silver Mitsubishi Mirage with a flat tire from the garage.
Some agents wore white biohazard suits; others wore coveralls and rubber gloves.
A supervisor at Kemper Aviation said Turki Almasri had been enrolled at the school, located at the airport in Lantana. It was not clear why federal authorities might be investigating the link now.
According to neighbors, the Almasris divided their time between Saudi Arabia and Florida, and would usually inform other residents when they were leaving. The last time, they apparently told no one.
Times staff writer Josh Meyer in Washington contributed to this report.