Even though they should be, detectives are not required to be honest with defendants in order to get them to turn themselves in.  This means that he may or may not be telling you the truth.  If he is misrepresenting what will happen, you will have no recourse if he has a warrant and bail is set at an amount that you cannot afford.  If you know there is a warrant, you don't want to dodge and appear difficult. But before you surrender on his terms, you may want to visit with a local criminal defense attorney to see how trustworthy this particular defendant is.  They may be able to do more to "walk you through" than the detective.