I was never a fan of that poisoned drink example. The second robot killed the human in a similar way to the drink itself, or a gun if one were used instead.

The human made the active decisions and took the actions that killed the person.

A much better example is a human giving a robot a task and the robot deciding of its own accord to kill another person in order to help reach its goal. The first human never instructed the robot to kill, it took that action on its own.