Sources say the twisted fragments have been traced to a Mitsubishi truck. Those pieces plus other evidence gathered at the U.S. embassy in Tanzania will be flown back to Washington this weekend in separate aircraft for analysis at the FBI Crime Lab, reports CBS News Correspondent Jim Stewart.
Meanwhile, Kenyan and FBI investigators are questioning several people who were reportedly spotted acting suspiciously shortly before the Nairobi blast.
Peter Mbuvi of the Kenya Investigation Division said, "There are about five of them. We are talking to them. We are questioning them, interrogating them."
Sources say U.S. agents thus far regard the five suspects as a "viable lead" but that other, possibly even stronger leads were being aggressively pursued.
Investigators are also exploring the possibility that the men who actually drove the Kenyan truck bomb may have been among the wounded and dead who were rushed to local hospitals and morgues. Investigators are now checking many of the survivors' stories.
"Over 20 investigative teams, consisting of one Kenyan police officer and one FBI special agent, have been established and even now conducting interviews of critical witnesses and victims of the
explosion," said Shiela Horan of the FBI.
In addition, eyewitnesses in Tanzania and Kenya will soon be paired with FBI sketch artists and 3D computer image specialists to help draw composite pictures of possible suspects.
There are unmistakable signs that federal agents are starting to make far more progress in this case than would normally be suspected so early in an investigation. Despite all the bomb damage, they've recovered important evidence. And, despite the chaos at the scene, sources say witnesses have come forward with critical new information.
Reported by Jim Stewart