The poisoned bullet would most likely be the cause of death.
The poison, the bullet, the gun, and the person who fired it are all responsible.
But take way the poison from the bullet. Then, the thing that was shot would have survived. So, it wasn't the bullet, the gun, or the person who fired the gun that killed the creature. But, add poison to the bullet, and that creature dies from the poison. Using this logic, we can say that the poison was responsible for the death of the creature.
No
Would you hold the car responsible when someone hits a pedestrian?
The poison doesn't kill on its own. It is used as a tool/weapon to kill plants
