Newswise — While Americans are celebrating the death of Osama bin Laden, a terrorism expert at Indiana State University says the Al Qaeda leader's death at the hands of U.S. forces could lead to retaliatory attacks against Americans and American interests.

"It just adds to the list of grievances. The killing of bin Laden has the potential to resonate in the streets and the cell blocks of U.S. prisons," said Mark S. Hamm, a professor of criminology and criminal justice who has studied the growth of Islamic extremism in prisons. "I don't think this killing indicates that this ‘war' is anywhere near over. It's just another stepping stone. For certain elements, it may have a radicalizing effect."

The U.S. State Department has warned Americans traveling abroad to be alert for possible retaliation. Americans would be wise to be cautious even if they're not leaving U.S. borders, Hamm said, especially if they live in or are visiting major cities.

"Heightened alerts are warranted both internationally and within the U.S. The potential for an attack comes more from our own homegrown jihadist groups rather than Al-Qaeda central. During the last 10 years, Al-Qaeda has evolved into an international ideology rather than a central organization. A cell may be self-activated in major cities such as New York," Hamm said. "I just came back from Scotland Yard and the Ministry of Justice in England and they were working on numerous potential threats. I would imagine the threat is much greater there now."

Ayman al-Zawahiri, an Egyptian-born doctor who is Al-Qaeda's second-in-command, is likely to succeed bin Laden, Hamm said, noting some writers trace al-Zawahiri's radicalization to being tortured in an Egyptian prison.

Hamm's research on radicalization with U.S. prisons included a study of California's Folsom Prison between 2005 and 2007 where inmates are triple-bunked.

Prison overcrowding and how inmates are treated can play a big role in radicalization of inmates, he said, noting the problem is virtually non-existent in institutions that are well-managed, adequately staffed and not overcrowded.

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