Do Criminals Deserve Justice?

It could be the plot-line of a John Grisham novel...the country's biggest armed robbery. Long jail term. Father tries unsuccessfully to clear son's name. Years later, son dies of natural causes. Father told by 'underworld sources' that son was actually poisoned.
But it's real. Charles "Chas" Willoughby served time for the 1984 holdup of an armoured truck on Auckland's North Shore, though he always claimed he wasn't involved in the heist: the raid netted a record $294,524.
When he died, a decade after his release, his family was told it was by natural causes: no autopsy was performed. Now his father, Charles Willoughby snr, has been approached by one of Chas' former associates and told his son died after his drink was poisoned. He was even given the name of the alleged murderer: that person no longer lives in New Zealand.
Following this shock, Charles spoke to Chas' colleagues, but was told to "let sleeping dogs lie". That's made him more suspicious about the true cause of death, and he now wants his son's remains examined.This process may be sped up if police decided to open an investigation into Chas' death.
Chas consistently denied he was guilty of robbery. While Chas did get some of the robbery money, Charles believes he didn't take part in the armed stickup, as his son's speciality was safecracking. He spent thousands on an unsuccessful appeal over his son's conviction. While his son was no angel, Charles is determined to get justice if he had been fatally poisoned.
Personally, I hope Charles is granted permission for the exhumation - for his own peace of mind, and for some final closure. And if poisoning is in evidence, it is hoped police will investigate further. While some may say "live by the sword, die by the sword", regardless of Chas' criminal activities he did not deserve to die in such an alleged manner. Society has evolved a system of justice that no-one can step outside without consequences.