It is unclear what the scope of the investigation is, or whether the league, which declined to comment, is acting on information other than reports in the news media. The investigation follows one of the most tumultuous off-seasons in N.B.A. history, with many high-profile players switching teams. The N.B.A. is also exploring whether it needs to change its rules against tampering.
Several players committed to signing with a team as soon as free agency negotiations officially opened at 6 p.m. on June 30 — even though teams were not allowed to begin recruiting before then. League rules prohibit players, coaches and front office executives from enticing an athlete under contract with another team to come play for their franchise.