Updated

FBI Director Robert Mueller (search), who days ago said the United States had turned the corner in the war on terror, dispatched a team of agents Tuesday to assist Saudi Arabia in the investigation of deadly new bombings.

The FBI "assessment team" that is headed to Saudi Arabia includes up to a dozen agents and technicians and is led by a senior official in the counterterrorism division. The FBI also has a permanent legal attache in Riyadh (search) who acts as a liaison with that nation's police and counterterrorism officials.

FBI investigators plan to interview witnesses and recover and secure evidence alongside Saudi police. FBI bomb specialists will begin the process of figuring out what explosives were used, how they were detonated and how to trace their origin.

"We have a team that will be going to Saudi Arabia fairly shortly to help our counterparts in Saudi Arabia to determine who is responsible for this," Mueller told reporters during an appearance in Albany, N.Y.

Tom Baker, former FBI legal attache in Paris, said investigators could obtain fingerprints from bomb fragments and compare them with those of known terrorists and with those found on fragments from previous bombings. Methods of wiring and the type of explosives used are also key clues.

"You can gather the evidence and use it to provide intelligence that links you to other people," Baker said.

The FBI is depending on cooperation from the Saudis, who restricted agency access after the 1996 bombing of the Khobar Towers dormitory that killed 19 U.S. military personnel. It will be up to the Saudis to secure the scene and ensure no evidence is lost.

Saudi officials have been eager to blunt U.S. criticism that they have allowed Al Qaeda operatives to operate within the country. More than 300 suspected terrorist have been arrested in Saudi Arabia since the attacks, Saudi officials say.

"My expectation is that we will get full cooperation from the Saudis," Mueller said.

Mueller said the attack bears many "markings" of Al Qaeda, although he declined to definitely blame Usama bin Laden's terror network. Officials say the signposts include the high degree of coordination needed to carry out the attacks, the use of homicide attackers and the group's oft-stated aim of ridding Saudi Arabia of Western influence.

U.S. intelligence had indicated over the past few months that an attack in Saudi Arabia against American interests was possible and that it would be against "soft targets" rather than fortified military or government installations. Al Qaeda staged a similar strike on a nightclub in Bali, Indonesia, last October that killed more than 200 people.

U.S. authorities are trying to determine who directed the operation and inquiring whether senior Al Qaeda operatives, believed to be in Iran, played a role, according to Bush administration officials who spoke on condition of anonymity. Bin Laden's son Saad is thought to be among those in Iran.

The new attacks came less than a week after Mueller and President Bush said the United States had turned the tide in the war against Al Qaeda and other terrorist organizations. They cited the capture of leading Al Qaeda figures and successful wars in Afghanistan and Iraq as significantly weakening the organization.

Some terrorism experts said the optimism might be misguided. They noted Al Qaeda is known for its patience and tends to mount major attacks in 18-to-24 month cycles.

"The very terrorist group we thought was on its way out pulls a sophisticated operation right in the heart of the Middle East, where we have thousands of troops," said Michael Greenberger, a former Justice Department counterterrorism official who is now a law professor at the University of Maryland's Center for Health and Homeland Security. "I'm very concerned about whatever intelligence they're getting that says the tide has turned."

Mueller said Tuesday that the United States has made "substantial strides" in combating Al Qaeda by removing their sanctuary in Afghanistan. "The fact that we have been successful in these areas does not completely eradicate Al Qaeda," he added.

In the Khobar Towers case, the FBI was prevented by Saudi officials from interrogating some suspects. Former FBI Director Louis Freeh urged former President Clinton to push for more cooperation, but the administration was concerned about offending a key ally.

At one point, the FBI had to submit a list of 212 questions to Saudi authorities, who then did the interviews with suspects while FBI agents watched.

A five-year FBI investigation led to the 2001 indictments in the United States of 14 suspects described by prosecutors as members of Saudi Hezbollah, an Iranian-backed terrorist group. None of the suspects has been brought to the United States to stand trial.