The man, in his 40s and a long-time resident of the canton of Geneva, preyed mostly on women working in erotic massage parlours, the broadcaster said in a news report.
He tricked them into giving him money for fictitious real estate investments, according to a justice department spokesman.
A total of around 20 people have filed complaints over the man since 2012, department spokesman Darrio Zanni told RTS.
Zanni said the suspected fraudster showed his victims plans of real estate projects but they were unconnected with the investments.
The victims have largely modest means and some of them lost their life savings, he said.
The cantonal prosecutor’s office believes it possible that other victims will step forward.
The money defrauded from the victims has been all spent, RTS said.