The presence of pre-existing, simultaneous or supervening causes, even though independent of the act of omission of the offender, shall not exclude a causal relationship between his act or omission and the event.
Supervening causes shall exclude a causal relationship when they were in themselves sufficient to bring about the event. If, in that case, the act of omission previously committed itself constitutes an offense, the punishment prescribed therefor shall be applied.
The preceding provisions shall apply even when the pre-existing, simultaneous or supervening cause consists of the unlawful act of another person.