Even when a criminal knows that they are in no danger of being found out, they continue to be haunted by misgivings. Did someone see them? Did they leave a clue to their identity at the scene of the crime? The processes they have set in motion are reflected in their consciousness and destroy their inner peace.
So, it is clear: as soon as you do something dishonest, all kinds of worrying images crowd onto the screen of your consciousness and destroy your peace of mind. If a person is guilty, their conscience will never be in peace however much they try to soothe it, because it is not their conscience that is at fault; it can only reflect the reality of their behaviour.
The source of the problem is the debt they have incurred. As long as that person has not made amends for their mistakes, their conscience will never be clear.