The term “lone wolf” was popularized in the 1990s to refer to an extremist who acts alone to avoid incriminating others. American extremists are often lone wolves, and many of these wolves were active in 2009. In May, anti-abortion activist Scott Roeder killed a Kansas abortion provider. One month later, Abdulhakim Muhammed shot two soldiers, killing one, outside a Little Rock Arkansas recruiting station in anger over the wars in Iraq and Afghanistan. Later in June, self-proclaimed white supremacist and anti-Semite James von Brunn, who recently died in prison at age 89, killed a security guard at the U.S. Holocaust Memorial Museum in Washington, D.C. Finally, in October, Army Maj. Nidal Hasan killed 13 service members at Fort Hood, Texas.
http://www.armedforcesjournal.com/2010/02/4445592