Since the U.S. raid that killed Osama bin Laden, Pakistani authorities say they have rounded up scores of people in Abbottabad on suspicion of having ties to the two people who protected the world's most wanted man.
Officials have been looking for anyone who knew Arshad Khan, the courier who managed Bin Laden's compound and who inadvertently led the U.S. to it, or his brother Tariq. Both men died along with bin Laden in the U.S. raid earlier this week.
Two Pakistani government officials say the official number of arrests is 31 so far. A separate Pakistani official in Abbottabad, however, told ABC News the detentions began soon after the Sunday night raid and netted as many as 200 people.
Local police participated in the sweep, with federal forces, including agents of the Inter-Services Intelligence service, or ISI. Intelligence officials here often detain people for questioning and quickly release them without charge, and that appears to have already happened in this case.
Among those taken into custody was the man believed to have designed the secure complex and acted as the project's contractor when it was built in 2005. One Pakistani official named the man as Tahir Javed, though his identity could not be verified. Pakistani officials and local residents say the contractor has since been released.
Another person of interest to authorities was a major local landowner named Shamroz who owned several plots next to the bin Laden compound. Neighbors described Shamroz and his sons as the people who knew the al Qaeda courier and his family best. Shamroz and his two sons have reportedly been arrested.
What Did the ISI Know?
Pakistani authorities have called the sweep the "second phase" of the operation that killed bin Laden, though Pakistani officials have been accused of knowing about bin Laden's presence in the Abbottabad compound, where's he thought to have lived for five years.
The high security compound is 1,000 yards from Pakistan's chief military academy, close to other military installations and in a neighborhood popular with military officials. Abottabad itself is less than 100 miles by road from the Pakistani capital of Islamabad.
On Thursday, defense undersecretary for policy Michele Flournoy said the U.S. could not prove the Pakistani government knew about bin Laden's presence in Abbottabad.
"We are still talking with the Pakistanis and trying to understand what they did know, what they didn't know," she said. "We do not have any definitive evidence at this point that they did know that Osama bin Laden was at this compound."
But Sen. Carl Levin, D.-Michigan, chairman of the Senate Armed Services Committee, told ABC News Thursday he believed senior Pakistani officials knew bin Laden's location and said he had "no doubt" they also know where other top terrorists are, including Taliban leader Mullah Omar.
"At high levels, high levels being the intelligence service, at high levels they knew it," Levin said in an interview for ABC's Subway Series with Jonathan Karl.
Levin is the highest ranking U.S. elected official to accuse the Pakistan government of knowing Bin Laden's whereabouts.
"I can't prove it," Levin said. "I can't imagine how someone higher up didn't know it." The Armed Services Committee, Levin said, has already started a preliminary investigation into Pakistan's involvement and, based on that investigation, will make a decision on holding public hearings to investigate further.