ESPN and The Athletic reported that NBA front office workers briefed staffers of members of the US House of Representatives Energy and Commerce Committee.
US lawmakers were absent due to the federal government shutdown and NBA commissioner Adam Silver also did not attend, according to the reports.
The committee had made a written request for a briefing to the NBA last month in the wake of the arrests of 34 people including Rozier, Billups and former NBA player Damon Jones.
Both players were placed on administrative leave by the NBA.
Subjects expected to have been spoken about included the league's partnerships with sportsbooks and how private information regarding teams and games in safeguarded.
Concerns regarding Rozier and Jones involved shared inside information with bettors who placed wagers and won.
Billups was involved with luring players into poker games where organizers used high-tech means to fix the outcomes.