US authorities announced several high-profile arrests on Thursday, including of a star player and a coach in the National Basketball Association (NBA), for alleged illegal sports betting. Among those in custody are Portland Trail Blazers coach Chauncey Billups and Miami Heat player Terry Rozier, both of whom were reportedly arrested after their teams' games on Wednesday.

The arrests are part of a sweeping investigation into illegal gambling that produced two indictments, the FBI said — one into players who are allegedly faking injuries to influence betting odds, and another involving an illegal poker ring tied to organised crime.

Here is what we know about the cases.

What are the allegations?

FBI Director Kash Patel described the allegations to reporters as mind-boggling. They include indictments in two major cases, both involving fraud. The first case is called operation nothing but bet, in which players and associates allegedly used insider information to manipulate wagers on major sports betting platforms.

In some cases, players altered their performance or took themselves out of games to ensure those bets were paid out, according to New York City police commissioner Jessica Tisch. Those bets amounted to tens of thousands of dollars in profits.

The second case is more complex and involved four of the five major crime families in New York as well as professional athletes. The accused in that case are alleged to have participated in a scheme to rig illegal poker games and steal millions of dollars, using sophisticated technology including X-ray tables to read cards that were face down.

Which players have been arrested?

All in all, authorities say 34 defendants were indicted on charges related to the two fraud cases. Six were charged in the first case of players allegedly faking injuries to influence betting odds, including Miami Heat player Rozier.

Authorities identified a total of seven NBA games between February 2023 and March 2024 that were part of the case. The second case related to illegal poker games involved a total of 31 defendants, including coach Billups, who was inducted into the basketball Hall of Fame last year.

What has the NBA said about the allegations?

In a statement on Thursday, the NBA said it is in the process of reviewing the federal indictments that were announced and that it is co-operating with authorities. The league added that Rozier and Billups are being placed on immediate leave from their teams and emphasized that they take these allegations with the utmost seriousness.

Who are New York's notorious 'Five Families'?

Authorities said the alleged scheme involved four of the five well-known crime families of New York. These crime families have ruled the city's Italian American mafia since 1931. The current indictments highlight that the mafia's presence still looms large, as they continue operations in illegal gambling and beyond.