Job one for intelligence analysts searching the "motherlode" of information grabbed from Osama Bin Laden's lair is finding any plans for imminent al Qaeda terror attacks.
But after attack plans, what U.S. authorities want to know is the whereabouts of Bin Laden's top deputies, especially the man who now could inherit the dual titles of al Qaeda's leader and America's most wanted terrorist -- Ayman al-Zawahiri.
"After attack plans," said former White House counterterrorism advisor and ABC News consultant Richard Clarke, "[they're looking for] the location of [Bin Laden's] deputies ... where the money is, where the money comes from, where does it live, and how big an organization is al Qaeda central these days?"
Though the FBI said it does not rank its most wanted beyond their presence in the top ten, the U.S. government is offering $25 million for information leading to the capture of the man it believes has been al Qaeda's true commander for several years – millions more than anyone else on the list.
Zawahiri, an Egyptian born doctor who turns 60 next month, helped found al Qaeda with bin Laden, merging bin Laden's group with his own Egyptian Islamic Jihad. Together they issued a fatwa in 1998, believed to have been authored by Zawahiri, called "World Islamic Front Against Jews and Crusaders," and also called a general meeting of al Qaeda.
Their shared career of terror began with the U.S. Embassy bombings in Kenya and Tanzania later that year, and continued with the USS Cole attack of 2000 and then 9/11. Zawahiri is under indictment in the U.S. for the embassy attacks.
In April 2009, the U.S. State Department said that it believed that bin Laden had become a spiritual figurehead within al Qaeda, and that Zawahiri, known as "The Doctor" or "The Teacher," was the group's true operational and strategic leader. Examination of the materials found in Bin Laden's Abbottabad hideout will show whether U.S. officials had it right. "Prior to the attack, CIA's impression was that Bin Laden was a passive manager who occasionally received reports," said Clarke. "We'll know better whether that was accurate when we see what was in the documents and on his hard drive."
A senior Pakistani official told ABC News Wednesday that Pakistan's intelligence agency, ISI, continues to believe that bin Laden had not been operationally involved with al Qaeda for some time.
Zawarhiri is still thought to be hiding near the Afghan-Pakistan border. Bin Laden was often said to be living in the same region, though when he was killed in a raid Sunday, Bin Laden had actually been holed up less than 100 miles from the Pakistani capital of Islamabad, right next to Pakistani military installations and the country's top military academy, for as long as six years.
Over the years, Zawahiri has released a drumbeat of audio and video messages via al Qaeda affiliated web sites, more than three dozen since 2003.
In his most recent message, an hour-plus long video posted online in April, Zawahiri calls on Arab armies to intervene in Libya to help eject dictator Moammar Gadhafi before "Western aid... turns into invasions."
The video was the first message in a year in a half from Zawahiri, and the first since Egypt's successful revolution. It features Zawahiri in a white robe with the barrel of an assault rifle visible at his side. In addition to discussing the bloody fighting in Libya, Zawahiri celebrates the overthrow of Egyptian President Hosni Mubarak and says that the continuation of the North African nation depends on the destruction of Israel and the establishment of Islamic law.
As a leader of Islamic Jihad in Egypt, Zawahiri had attempted to organize a coup against Anwar Sadat. Zawahiri was arrested, imprisoned and allegedly tortured by Egyptian authorities after Anwar Sadat's assassination. He served a three-year sentence on a weapons charge and moved to Saudi Arabia in 1985 on his release. After Saudi Arabia, he moved to Pakistan, where he met Bin Laden.
Prior to the April video, Zawahiri had lauded the revolts in Egypt and Tunisia in the latest issue of al Qaeda's English-language magazine "Inspire".
In February, in the midst of the Egyptian uprising, Zawahiri released a 34-minute audio message blasting the corrupt government under Mubarak.
Three years ago, Zawahiri also wrote a book that provided a religious justification for using weapons of mass destruction against America.
CIA director Leon Panetta said Tuesday that Zawahiri was "moving up very fast" on the U.S. enemies list, but noted that the U.S. needed to see for certain who would replace bin Laden as al Qaeda chief. The FBI also told ABC News it was "premature" to speculate on who would fill bin Laden's now-vacant position on the Most Wanted list.
White House counterterror advisor John Brennan said that Zawahiri lacks charisma and has enemies within al Qaeda. A former attorney of Zawahiri's in Egypt wrote a book about Zawahiri that portrayed him as abrasive, stubborn and arrogant, and said that would limit his effectiveness.