James Dunnigan explains how anti-terrorist forces are Recruiting the Dead, Missing and Unwilling:
While shutting down the terrorist bank accounts, or actually seizing cash, some more experienced investigators realized this provided an opportunity to cause additional damage to terrorist cells, especially if the guy in charge of the money was not caught. All you had to do is not give any publicity about the money seizure. Keep it quiet. There was a good chance that the terrorist responsible for the money would not be believed when he told his superiors that the money was seized, or otherwise disappeared as the result of counter-terrorist operations. Captured al Qaeda mail had disclosed a lot of angry queries to subordinates about what happened to money the underlings had been given. There were accusations of theft or misappropriation of funds, some of them later found to be accurate. After 2001, al Qaeda had less reliable communications, and fewer troubleshooters they could dispatch to branch offices, to clear up problems with missing money. Paranoia and nervousness were on the increase because of the American, and world, response to 911.The increased tension in post-911 al Qaeda cells provided other opportunities as well. Some al Qaeda members now wanted out, but the closer you were to the core members, the more difficult it was to get out. So counter-terrorism officials made it easier for terrorists to leave the business. While not exactly a witness protection program, arrangements could be made to move the repentant, or just burned out, bad guys to safety. With so many Moslems communities in the West, this is a lot easier. In some cases, the terrorists were turned (into double agents), and provided information to their handlers.
Captured terrorists also provided other opportunities. After 911, and even with the Internet, al Qaeda communications were poor, as was their intelligence work. Bottom line was, most al Qaeda members were never sure if a fellow terrorists had been killed in action, captured or defected. Because of this, even dead terrorists could be useful to counter-terrorist operators. You could keep a dead terrorist ‘alive’ on the Internet for a while, or in the minds of other terrorists being interrogated at places like Guantanamo. And then there was the classic interrogation trick, threatening to frame a terrorist as an informer, and release him. If done well, this was a formidable weapon, for it threatened the terrorist with a fate worse than death, to be tagged as a traitor.