Killing anybody won't go uninvestigated and punished. And here the person is the mighty and influential PK. So definitely there is gonna be an investigation.
Rather than killing him, Pooja should have forced him to confess to the public abt Dr. Ashok Sharma's innocence. It was very much required and there is no one better than PK to do that.
And anyway she has brought the entire family to the streets. That itself is humiliating and unbearable for someone who has led a luxurious life.