David Stern, the N.B.A. commissioner, is expected to hold a news conference this week ? perhaps as early as today ? to discuss the league?s involvement in the F.B.I.?s gambling investigation of the referee Tim Donaghy.

According to two people briefed on the investigation, the N.B.A. had no knowledge of Donaghy?s betting and questions as to whether he influenced the outcomes of games until after the season. These people spoke on condition of anonymity because the investigation was still under way.

Donaghy last worked May 12, in Game 3 of the Western Conference semifinals between Phoenix and San Antonio.

N.B.A. referees are prohibited from betting on any sport; sufficient evidence of gambling would result in immediate termination. Donaghy is no longer working for the N.B.A.