This is purely hypothetical:
A person announces their intent to attack another with "magic", telegraphing what witnesses consider a "spell". It's broad daylight with numerous witnesses and surveillance footage. The victim then immediately suffers a miraculous death that can't be explained by science (all their blood turns to tar, they spontaneously dissolve to viscera, or they simply drop dead for no discernible medical reason)
Could the "magician" be found guilty of any crime greater than verbal assault if no causation link between the attacker's incomprehensible action and the victim's death is found?