Two last-minute rescheduled flights, $7,000 in cash, and a bag full of knives, watches and cell phones taped to bottles of liquid.
His luggage, packed with a cell phone taped to a bottle of Pepto-Bismol, a box cutter, large knives, and watches also taped together, arrived intact at Dulles International Airport, without their owner, according to authorities.
Was al Soofi carrying out a dry run to test which items would be detected? To see at what point he would be stopped?
A U.S. government official, however, told the Associated Press that the FBI is finding that it's unlikely al Soofi and another man were on a test run for a future terror attack, even as Dutch authorities continued to hold the pair on suspicion of conspiring to commit a terrorist act.
The U.S. official said the two men arrested in Amsterdam did not know each other and were not traveling together.
The official, speaking on condition of anonymity to discuss the ongoing investigation, said both men missed flights to Dulles from Chicago, and United Airlines then booked them on the same flight to Amsterdam. The men were sitting near each other on the flight.
Another U.S. official, who also spoke on condition of anonymity, says that when Customs officials discovered one passenger was not on the flight from Dulles to Dubai, they called the plane back to the gate and removed his luggage. It was then they discovered
suspicious items in his bag.
Al Soofi was scheduled to fly from Chicago into Dulles. That flight would eventually go on to Dubai and Yemen. But not before customs officials found his luggage was not paired with an on-board passenger just before takeoff. The aircraft returned to the gate until the situation could be sorted out.
What caught the attention of investigators? During an early leg of the trip, al Soofi was stopped in Alabama. TSA officials thought his clothing looked "bulky." Al Soofi admitted to having $7,000 in cash on him, but investigators let him go on to Chicago.
There he changed his itinerary, booking a direct flight on United Airlines from Chicago to Amsterdam. His luggage -- carrying the phones, knives, and liquid -- went without him on a flight to Dulles.
In Chicago, authorities initially reported that al Soofi met up with another man, Hezam al Murisi, who changed his itinerary, as well. Those changes aroused suspicion, too.
In a statement, the Department of Homeland Security confirmed the following:
"Suspicious items were located in checked luggage associated with two passengers on United Flight 908 from Chicago O'Hare to Amsterdam last night. The items were not deemed to be dangerous in and of themselves, and as we share information with our international partners, Dutch authorities were notified of the suspicious items. This matter continues to be under investigation."
Separately, a U.S. official said, "Many of the details in current news stories are based more in rumor than fact. The individuals did not have prohibited items on their persons or their carry-on luggage."
The official also said neither of the two men was on a no-fly list nor in any terrorism database. And three federal Air Marshals were on their flight.
Tuesday morning, White House spokesman Robert Gibbs promised "a vigorous investigation.''
American passengers arriving in Amsterdam from the United States on Tuesday appeared to take the news of the arrests in stride.
"There is always going to be problems but I think that the system in terms of security works pretty well. I am traveling all the time and I feel pretty safe," Steve Harriot of Chicago told AP Television News.