How does Brutus Jones attack the prison guard?

Brutus Jones has been sent to prison for murdering a fellow Pullman porter called Jeff over a gambling dispute. While serving time, Brutus is forced to toil away as part of a road gang. One day, he attacks and kills a prison guard with a shovel before making his escape. After he arrives on the island as a stowaway, Jones is never quite able to shake off the haunting memories of the two murders he's committed.
Later on in the play, when he tries to escape from his irate subjects, the "Emperor" Jones encounters the ghosts of Jeff and the prison guard in a forest. He shoots at Jeff's ghostly apparition, which then vanishes. He then reenacts the murder of the prison guard before shooting at the prison guard's ghost to try and ward it off. But try as he might, Jones just cannot escape from his past, either from his own past or the past of his oppressed race, which both follow him around wherever he goes.