The NFL is reportedly investigating a fresh wave of gambling policy violations among its players. ESPN’s David Purdum reported the news on Monday, with the specifics of the investigation still unclear.

Five NFL players received suspensions in April for gambling-related infractions. Three of them were hit with indefinite suspensions because they wagered on league games, while the others received six-game bans as they were placing wagers while at a team facility.

the league’s policy on the matter is clear

Speaking to ESPN, NFL Vice President and General Manager for Sports Betting David Highhill said the league’s policy on the matter is clear, despite acknowledging that it can be challenging to enforce these rules. This month, the NFL confirmed that it is utilizing its sportsbook partners to ensure players are not wagering, but there are ways around this.

Players can place bets through an offshore sportsbook or a local bookie, who have no obligation to report the betting activity to the NFL. Players could also get friends to place wagers on their behalf. Despite the growing interest in sports betting, the league has not found any indication of game manipulation in recent years.