11.   The Pearl case is the most complicated of the recent school killings because of the number of students involved.

12.   The reality is that there are very few school killings in the United States.

13.   Yet she admits that the recent school killings have elements of both.

14.   Commemorations of the first anniversary of the worst school killing in U.S. history at Columbine High School.

15.   Dunblane, still coping with a school killing.

16.   He delayed announcing his retirement because of the school killings in Littleton, and his news conference began with a moment of silence for the victims.

17.   On Tuesday, hundreds of demonstrators rallied outside a Manson concert in Minneapolis, protesting possible links between his dark music and the Colorado school killings.

18.   Meanwhile questions were being asked as to how the worst school killing in British history could have been prevented.