if a person had told an informant,( not knowing they were an informant ) that they were waiting for person ( says name) to sell him drugs , informant tells cops , cops arrest person . police want information from the person saying the name , to admit that they had told this informant this persons name ,along with other information , and the person denys ever saying anything . so cops threaten to charge that person , with conspiracy to attemped to commit a crime . reads the person his miranda rights . person still denys ever saying anything , cop lets him go . my question is can the cop really charge that person with said crime , or was the cop trying to scare person so he would talk?