Is it legit or am I just extremely paranoied that a malignantly narcissistic ex-friend of mine wants 2 harm me

In the past he would "jokingly" tell me how one day he could kill me and brag about how he would one day be a famous serial killer. He recently contacted me after almost 2 years of not hearing from him, and now I'm scared that I've been on his mind. He is extremely narcissistic and needs to be praised all the time. He can not take criticism and believes he is destined to be great when in fact he is a bum with nothing going for him. He has absolutely no empathy to speak of which really bothers me, and he gets very jealous. Once time goes by and I have my successful career up and going and he has no future I fear he will try to take it away from me in jealousy by killing me. the only thing giving me some comfort is that I've told numerous people that if I ever mysteriously get killed that they should report him for murder, and that will give me some peace in the afterl;ife knowing that this sbag won't get the fame that he so desires. This bothers me all day every day.