A 32-year-old man was indicted on 39 counts of wire fraud.
Justin Wade Smith is accused of stealing more than $1 million from dozens of victims.
According to the Federal Bureau of Investigation, Smith told people he was an heir to a big trust fund, but needed money to get the inheritance.
Smith promised them a big return for their help, but the FBI says it was all a lie.
So far, more than 30 victims have come forward in Hawaii and Las Vegas, but authorities believe there may be more.
Anyone who believes they may have been victimized by Smith is asked to contact the FBI office in Kona at (808) 329-5106.
Smith pleaded not guilty.
His trial is set for October.