What is the importance of the Colva Prison in the novel, Trash?

Colva Prison is located in one of the crumbling parts of town, a place that even puts Behala to shame. The prison requires bribes to enter and is full of people stuffed into cells in stifling hot conditions, including children. Gabriel Olondriz was imprisoned here after he tried to convict Senator Zapanta for corruption, and he died in the prison as well.