11.   For the first two days the hijackers were jumpy and brusque, hostages said.

12.   He knew as soon as word surfaced that the hijackers were most likely Muslim that there would be a backlash.

13.   He said two more hijackers were in the cockpit, while the fourth was guarding the first-class cabin.

14.   I was told the hijackers were actually educated in America.

15.   Initial reports had suggested that the hijackers were Sikhs.

16.   Mellin suggested a connection to the hijackers, emphasizing that there were five hijackers on the hijacked flight.

17.   Nineteen suicide hijackers were on board American and United flights that went down.

18.   Officials initially thought there were three hijackers, because two people were seen looking out of the rear of the plane after it arrived in Barcelona.

19.   The alleged hijackers have been dead more than six weeks and their temporary residences were combed by authorities and later rented out to others.

20.   The caveats take on critical significance in the World Trade Center attacks because all the hijackers were male and obtaining samples from sisters or mothers seems unlikely.