What if the inspector finds a dangerous defect in the property? Who does he tell?

As your advocate, he will, of course, tell you. Depending on the nature and degree of the defect (i.e. seriously leaking natural gas from a corroded pipe) he is obligated to tell the owner as soon as possible so they may take action to repair the defect immediately. If they cannot be reached, he may take the initiative to call the respective utility company so they may shut off the service before catastrophe strikes. Again, depending on the serious nature of the problem, all occupants of the building should be informed and perhaps evacuated.