U.S. authorities on Thursday unsealed a 252-count grand jury indictment charging 80 people in a major conspiracy to steal millions of dollars through fraud schemes and launder the money through a Los Angeles-based network.
Most of the defendants are Nigerians, the U.S. Attorney's Office said.
"We believe this is one of the largest cases of its kind in U.S. history," U.S. Attorney Nick Hanna told a news conference.
The conspiracy included frauds involving business email, romance scams and schemes targeting elderly people.
Victims were targeted in the U.S. and around the world, and some lost hundreds of thousands of dollars.
Fourteen defendants were arrested, mostly in the Los Angeles region. FBI agents could be seen processing suspects in a downtown Los Angeles parking lot.
Six other defendants are believed to be fugitives in the U.S. and the others are abroad, mostly in Nigeria. Authorities said they hope to extradite them.
The investigation began in 2016 with one victim and a single bank account, said Paul Delacourt, assistant director in charge of the FBI's Los Angeles office.