There is a lot of speculation, questions and explanations about the title of the book.
I received one such question/opinion from an expert in the USA and referred it to the author and received the reply quoted at the bottom:
Received by email:
An interesting observation - I presumed the title "Fruit of a Poisoned Tree" came to the mind of Antony based on a US legal ruing, cited in a Supreme Court case, but from looking at the scripture quotation in the beginning, it appears it might not have.
The term "Fruit of the Poisoned Tree" in US legal jargon and is explained below. If as a result of something illegal, i.e. search without a warrant, illegal arrest, etc., the police then discover additional evidence that is incriminating, that additional evidence would not be allowed in court. Although in the case of Fred, all the evidence was either fabricated or otherwise misused or mis-evaluated, I thought you might want to know how the term is used. See further explanation below.
For instance - "The "fruit of the poisonous tree" doctrine is an offspring of the Exclusionary Rule. The exclusionary rule mandates that evidence obtained from an illegal arrest, unreasonable search, or coercive interrogation must be excluded from trial. Under the fruit of the poisonous tree doctrine, evidence is also excluded from trial if it was gained through evidence uncovered in an illegal arrest, unreasonable search, or coercive interrogation. Like the exclusionary rule, the fruit of the poisonous tree doctrine was established primarily to deter law enforcement from violating rights against unreasonable searches and seizures.
The name fruit of the poisonous tree is thus a metaphor: the poisonous tree is evidence seized in an illegal arrest, search, or interrogation by law enforcement. The fruit of this poisonous tree is evidence later discovered because of knowledge gained from the first illegal search, arrest, or interrogation. The poisonous tree and the fruit are both excluded from a criminal trial."
After forwarding the above to Antony Altbeker he replied with:
The title is supposed to suggest a whole lot of things. One of those is the legal question of evidence obtained under unlawful circumstances. Of course, this is not what happened in Fred's case, but most readers won't know that until late in the book when i explain it. More importantly, I'm trying to suggest in the book that the conduct of the police has its roots in the organisational culture of the institution which, in turn, has its roots in the nature of policing in SA for the past few generations. There is also the biblical allusion, which, as you know, plays into a sub-theme of the book.