Cairo (CNN) -- Investigators in Egypt said a man they seized Wednesday is a wanted for terror-related crimes, but he is not Saif al-Adel, a notorious leader in the al Qaeda terror network.
Authorities arrested Mohamed Ibrahim Makkawi at Cairo's airport after he arrived on an Emirates Airlines flight from Pakistan.
The FBI lists "Muhamad Ibrahim Makkawi" as an alias for al-Adel, who briefly led al Qaeda and was indicted for his role in the 1998 bombings of U.S. embassies in East Africa. Egyptian authorities initially thought the man arrested might be al-Adel.
But Interior Ministry spokesman Gen. Marwan Mustapha said Al-Adel and Makkawi are "two different people." Makkawi has been wanted on charges of terrorism and conspiring to topple the regime, he said.
"There is obvious confusion of data among security apparatus and the media," Mustapha said.
Omar Ashour, director of Middle East Studies at the British-based Institute of Arab and Islamic Studies, said the confusion could have arisen because both Makkawi and al-Adel served as Egyptian army officers and have ties to al Qaeda.
Mohamed Abdel Rahman, a former jihadist, told CNN he knows both men. He fought alongside Makkawi in 1989 in Afghanistan, he said.
Two U.S. officials who are not authorized to speak on the matter said they doubted the man arrested man was al-Adel.
Al-Adel's arrest would have been another major blow to al Qaeda, which already is reeling from the death of Osama bin Laden and the capture or killing of other senior leaders. The United States has offered a reward of $5 million for information leading to the capture of al-Adel.
An Egyptian citizen, al-Adel was indicted for his alleged role in the August 1998 bombings of U.S. embassies in Tanzania and Kenya, according to the U.S. State Department. The bombings killed 224 civilians and wounded more than 5,000 others.
Al-Adel faces charges including conspiracy to kill U.S. citizens; conspiracy to destroy U.S. buildings and property; and conspiracy to destroy U.S. national defense utilities.
A former Egyptian army lieutenant and longtime Islamist, al-Adel was appointed the interim leader of al Qaeda after Osama bin Laden's death. Ayman al-Zawahiri eventually took the helm of the organization.
Peter Bergen, CNN's national security analyst, said al-Adel is the military commander of al Qaeda and has been involved with the group since it was founded in the 1980s. He said the U.S. government would be eager to talk to him. He'd be "gold mine" of information about al Qaeda activities.
"He is enormously important to the group. He was reported to have briefly taken over leadership of al Qaeda after bin Laden's death while they spent six weeks deciding who the leader is. Arguably he's more important than the actual leader of the group, Ayman al-Zawahiri," Bergen said..
Bergen said al-Adel had been under house arrest in Iran "arguably since 2002." But he thinks al-Adel was let go at the end of 2010.
"He then made his way to the tribal areas of Pakistan," Bergen said.
James Clapper, director of national intelligence, said this month that "the death or capture of prominent al Qaeda figures since bin Laden's death has shrunk the layer of top lieutenants directly under Zawahiri."
He said "core" al Qaeda, the Pakistan-based group once led by bin Laden, is in decline. He made these remarks in the U.S. intelligence community's worldwide threat assessment.
"Core al Qaeda's ability to perform a variety of functions -- including preserving leadership and conducting external operations -- has weakened significantly," he said, and it will "suffer sustained degradation" and "decreasing influence" with persistent counterterror pressure.
Clapper said regional al Qaeda affiliates such as al Qaeda in the Arabian Peninsula in Yemen, al Qaeda in Iraq, al Qaeda in the Islamic Maghreb in northern Africa, and al-Shabaab in Somalia "will remain committed to the group's ideology" and "will surpass the remnants of core al Qaeda in Pakistan."