The two are linked closely with Giuliani, President Donald Trump's personal attorney.
Belarus-born Fruman and Ukraine-born Parnas, both US citizens and Florida residents, introduced Giuliani to former and current Ukrainian officials, and Parnas' company, Boca Raton-based Fraud Guarantee, paid Giuliani $500,000, he told Reuters.
Giuliani himself is a subject of the ongoing investigation by the federal prosecutors who charged Fruman and Parnas, a probe that is examining Giuliani's Ukrainian business dealings, CNN has reported.
Fruman and Parnas' co-defendants, David Correia and Andrey Kukushkin, who are each charged with one count of conspiracy, were arraigned last week and pleaded not guilty.
The-CNN-Wire & 2019 Cable News Network, Inc., a Time Warner Company.