How is johnny from the outsiders guilty for bobs murder?

Johnny Cade is guilty of manslaughter in the death of Bob Sheldon. The accused and main character in the S. E. Hinton novel The Outsiders was sent up the river for four years to Collins Bay Penitentiary Thursday during a mock trial at Gananoque Secondary School

Explanation:

mark twain, real name samuel langhorne clemens, was an american writer, humorist, entrepreneur, publisher, and lecturer. among his novels are the adventures of tom sawyer and its sequel, the adventures of huckleberry finn, the latter often called "the great american novel". wikipedia

i'm thinking it would be when compound subjects are joined by or, nor,either-or, neither-nor.