Just pursuing is not grounds for murder (either way fyi). Now if the shooter pursued and the shootee was unarmed yea thats very bad.
As I said I don't know anything about this case going to shut up now.
Defendant said he threatened his son with a gun. Teen did in fact have an illegal gun and was committing a felony. Seems clear.
What am I missing? I only know the case from the OP?