Why is this guy telling this lie on me?

Ok I am almost 27 years old, a guy who is 43 years old whom I have never been with sexually has went and told someone else I know that he is trying to hunt me down because he says he is the father of a 10 month old baby that is mine. I dont have a 10 month old baby and I never slept with him. He has changed his story (various parts) multiple times. Since I dont have a 10 month old baby and I havent slept with him for what other reason could he be willing to pay someone to locate me? Also why would he lie to that person saying that is the reason he is looking for me? I found out recently that the man who is looking for me is a sex offender.