Nothing can stop him from destroying the control system which forces the robots to kill.
Otherwise the robots would simply have killed us, instead of bringing us here.
Then, Yvette was sure, the robot would kill him without mercy even before her husband could react.
Eventually the robot kills both of them and stalks toward the audience in triumph.
"And a robot with a First Law built in could not kill a man?"
When the robot killed a UN researcher, the power brought him back to life.
The robot could return at any time, night or day, and kill one more person-or a thousand.
He's human - and a robot can't kill anybody!
But a man would be dead and a robot would have killed him.
Evidently the other robot had killed him before being downed in turn.