What if the officer promises you that you’ll get off easy or that he won’t tell anyone? 

The law says that police officers can lie when investigating criminal activity.  There is simply no way for me to ever count how many cases involve officers telling someone that they won’t be charged if they just come clean or admit they did something. 

Often times, upon hearing that assurance, people will say just about anything in order to end their encounter with an officer, expecting to go free.  Unfortunately that is usually just the beginning of the legal process.  The officer will then take that statement and use it against the person.  The legal process allows the officer to use deception to assist in the arrest and conviction.

Words out of your own mouth tend to be the most damning evidence, even if you are innocent.  The officer is not the ultimate charging authority, that is the job of the prosecutor.  The prosecutor does not have to honor any promise or assurance that the officer has made to you.