What is the theme in Heaven's Prisoners by James Lee Burke?

The dominant theme of the novel is driven by plot and is itself fairly simple—bad things happen because bad people act selfishly. The novel presents a nearly endless string of horrible occurrences, from the brutal murder of Annie to the earlier death of Dave's father—a death caused by insufficient safety precautions caused by cutting corners to make an oil company more profitable. The book discusses prostitutes being burned alive; prison inmates being homosexually raped; women being blown up by bombs; scenes of torture in Viet Nam; pregnant women by ritually murdered by machete; incessant drug, alcohol, and tobacco use; endless streams of prostitutes, con men, thieves, and human scum; and even senile old women being shoved down stairways. Beside all of these horrific details, the gunfight killing of Victor Romero seems a minor event involving some minor use of force. The knifing of Bubba seems a nearly idyllic end to a career of disgusting activity leaving a swath of destruction as a wake of personal prosperity.