First you need to be establish the definition of the term Murder;
'The classic definition of murder is that of Sir Edward Coke (Institutes of the Laws of England, 1797):
"Murder is when a man of sound memory, and of the age of discretion, unlawfully killeth within any country of the realm any reasonable creature in rerum natura under the King's peace, with malice aforethought, either expressed by the party or implied by law, so as the party wounded, or hurt, etc. die of the wound or hurt, etc. within a year and a day after the same."
For the purposes of convenience, we can say that murder is the unlawful killing of a human being under the Queen's peace with malice aforethought. However, death no longer need occur within a year and a day.'
From the above definition, murder is the deliberate act of taking the life of another, with the intent of depriving that person of life. Proof of this intent, is a vital difference between Murder and Manslaughter.
Although Bob may have been conditioned, by family influences, to accepting violence as the norm, this does not, in itself, predispose an individual to commit acts of violence. That involves a conscious choice, by the individual, to commit acts of violence.
One may speculate, upon the reasons for a particular act. However, only those who committed the act, hold the key to why the act was committed.
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