Osama bin Laden's death opens up a spot on the FBI's list of Ten Most Wanted Fugitives. But adding a name to the list is "not quite as simple as moving the No. 11 guy up a spot," says Ryan J. Reilly at Talking Points Memo. Here, a brief guide to how the list works:

What exactly is the Ten Most Wanted list?
The list was created in 1950, after a reporter asked "for the names and descriptions of the 'toughest guys'" the feds were after. The story that resulted got so much attention that then-FBI director J. Edgar Hoover made the list an official program. Its purpose is to generate publicity about "particularly dangerous fugitives," so ordinary citizens will know to alert the FBI if they spot the bad guys. And it works — out of the 494 fugitives who have been placed on the list over the years, 464 have been found, and in 152 of those cases, the capture came "as a direct result of citizen cooperation." 

When did bin Laden's name go on the list?
The al Qaeda leader was placed on the list on June 7, 1999, after he was indicted for his role in planning the August 7, 1998, bombings of the United States embassies in Dar es Salaam, Tanzania, and Nairobi, Kenya — which killed more than 200 people. After 9/11, intelligence agencies quickly determined that bin Laden's terrorist group had carried out the attacks, and in October 2001 his name was added to the State Department's Most Wanted Terrorists List, too. Bin Laden "has been the only person on both lists," according to Reuters.

Who else is on the list?
The list already includes an assortment of alleged murderers, robbers, drug dealers, and fraudsters. There's James "Whitey" Bulger, wanted in connection with Boston mob hits in the '70s and '80s, and Semion Mogilevich, an alleged investment fraud mastermind. Each new candidate must have "a lengthy record of committing serious crimes and/or be considered a particularly dangerous menace to society."

So how will the FBI replace bin Laden?
It has already updated the list provisionally, by placing a red banner reading "deceased" under bin Laden's picture. But replacing him will take "at least a few weeks," says Reilly at Talking Points Memo. The bureau will take nominations from the 56 field offices around the country. Once those names are in, a committee of representatives from the FBI's Criminal Investigative Division and its public affairs office will pick the next fugitive to add from those nominated names. The proposed replacement must be approved by the FBI director before officially being added to the list.

Who is likely to fill the vacant spot ?
If reward money is any indication, bin Laden might be replaced by his No. 2 at al Qaeda, Ayman al-Zawahiri, who is also wanted in connection with the 1998 embassy bombings. The $25 million reward being offered for information leading to his capture, says Erica Goode in The New York Times, is second only to the price that had been placed on bin Laden's head.

Sources: FBI (2), New York Times, Reuters, Talking Points Memo, Wall St. Journal