If a detective is following you within a dream, it may be a sign that other people want to know more about you. A dream about a police officer or army officer may suggest the importance of following correct procedure or correct behavior. Perhaps an aspect of your behavior in waking life is upsetting others?
Policemen can also represent the father figure, whilst a policewoman can bring to mind a dominant female in your life. A fireman relates to how you deal with your emotions or outbursts of energy.