A top U.S. law enforcement official acknowledged Thursday that investigators are not sure about the identities of several of the hijackers involved in last week's terrorist attacks.
Federal Bureau of Investigation Director Robert Mueller said Thursday FBI agents do have questions about the identities of some of the 19 hijackers who seized control of four jetliners on September 11. "We have several hijackers whose identities were those on the manifest [passenger list]. We have several others still in question. So, the investigation is ongoing and I am not certain as to [the identities] of several of the others," he said.
The discrepancies on the identities of some of the hijackers came to light after officials in Saudi Arabia questioned whether some of those involved in the terror plot had stolen identity documents from Saudi citizens.
FBI Director Mueller and U.S. Attorney General John Ashcroft toured the site in southwestern Pennsylvania where United Airlines flight 93 crashed, killing 44 passengers and crew members.
The passengers on flight 93 have been called heroes because cell phone calls indicate they fought back against the hijackers.
Attorney General John Ashcroft said the largest criminal investigation in U.S. history continues to make progress. "Developing a better understanding of what we can do to ensure that we disrupt, interrupt, stop, thwart, curtail the risk of further events like those events of Tuesday, September the 11. That is the responsibility that we labor incessantly on and we will leave no stone unturned," he said.
The FBI arrested another man wanted for questioning in connection with attacks outside Chicago late Wednesday. The man is on a list of wanted suspects who may have had links to the hijackers.
The FBI has now detained more than 100 people on immigration charges so that they can be questioned in connection with the September 11 attacks.