All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If this man is tricking others to steal their money and the like, then you are first obliged to advise him and warn him against persisting in doing so. You may either advise him directly if you are safe from being afflicted and do not fear to be harmed, otherwise you may advise him by any other means. If he does not take heed, you are obliged in this case to warn others from him and especially the Muslims. The Prophet said: "A Muslim is a brother of another Muslim, so he should not oppress him, he should not forsake him but should support and protect him, nor should he hand him over to an oppressor. Whoever fulfils the needs of his brother, Allaah will fulfil his needs; whoever brings his (Muslim) brother out of a discomfort, Allaah will bring him out of the discomforts of the Day of Resurrection, and whoever conceals the sins of a Muslim, Allaah will conceal his sins on the Day of Resurrection." [Al-Bukhari and Muslim]
Allaah Knows best.