The commissioner can't dismiss it anymore.

With his league facing its biggest scandal ever, Stern plans to hold a press conference tomorrow morning. The first question he must answer is what, and when, the league knew of former referee Tim Donaghy's gambling habits.

Donaghy officiated the last game of his 13-year NBA career during the San Antonio-Phoenix second-round series. Stern surely will be asked if the league could, or should, have known of Donaghy's problems by then.

The FBI is investigating Donaghy for allegedly betting on games he officiated during the last two seasons. He is expected to turn himself in at U.S. District Court in Brooklyn later this week or early next week, according to a person familiar with the investigation.

Authorities are examining whether the referee made calls to affect the point spread in games on which he or associates had wagered thousands of dollars over the past two seasons, according to a law enforcement official. The referee had a gambling problem and was approached by low-level mob associates through an acquaintance, the official said.

Another person with knowledge of the FBI investigation told The Associated Press the league was unaware of the inquiry until after the NBA finals. But the Denver Post reported Sunday that the NBA was made aware of the probe in January.

Those familiar with the investigation and the law enforcement official spoke on condition of anonymity because they weren't authorized to discuss the ongoing probe.

During All-Star weekend in Las Vegas, Stern was asked if the fear of point shaving was the reason for his stance against gambling. Stern quickly cut off the questioner and said: "I am not worried about games being fixed, and I'm surprised you asked the question."

Now, questions abound.

According to RJ Bell, president of the sports betting Web site Pregame.com, Donaghy's games went above the over/under line 57 percent of the time in the last two seasons after doing so only 44 percent of the time from 2003-05.

Perhaps more damaging, Bell found that in games where the spread moved at least 1 1/2 points, the team getting the big action covered in 10 straight games officiated by Donaghy from January through April of this year. The odds of that, he said, were 1,024 to 1.

Donaghy could have influenced the overs simply by calling more fouls. There have been reports that he topped the league in technical fouls called, but the NBA said today he ranked in the lower half of technicals called in each of the last two seasons.

He is the only referee, at this point, under investigation, according to a law enforcement official, but others outside the NBA are expected to be charged in the betting probe.

The investigation already has drawn plenty of unwanted attention.

Over the weekend, police staked out Donaghy's home in Bradenton, Fla., after he received two telephone threats. Both calls seemed to come from the same unidentified caller, Manatee County Sheriff's Office spokesman Randy Warren said.

Three squad cars arrived at Donaghy's home yesterday after he received the calls, according to a sheriff's office report. Donaghy did not have a listed phone number at his home.