“The vandal, who turned out to be the gunman’s stepson”
To me that is incidental and makes no difference.
Legally, that’s true.
However, it does complicate his domestic situation.
Whenever the shooter and the person shot know each other, it requires greater scrutiny.
Otherwise, most 1st degree murders would go like this.
1. Kick in own door.
2. Invite victim to home to show you their new gun, knife, bat, etc.
3. Shoot victim upon entry.
4. Call police to remove body.