A schoolboy who killed a senior teacher calmly accepted a suspension for driving on an athletics field hours before he opened fire with his policeman father’s gun.

An angry online posting from the 17-year-old boy who opened fire at a Nebraska high school, killing an assistant principal before shooting himself dead, offers some clues about why he turned violent.

The deputy head gunned down by a pupil during a school shooting rampage lost her fight for life today.