According to a law enforcement official, 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.

The referee had a gambling problem and was approached by low-level mob associates through an acquaintance, said the official, who spoke to the AP on condition of anonymity because he wasn't authorized to discuss the ongoing investigation.

Gambling long has been a problem in sports, and leagues have made a point of educating players of the potential pitfalls. The NBA, for example, discusses gambling at rookie orientation, even bringing in former mobster Michael Franceze to speak.

And the NBA dealt with negative stories about its officials earlier this year when an academic study detailed a bias by referees against players of the opposite color. The league requires its officials to file reports and defend or discuss every questionable call they make in a game.

Donaghy, who reportedly has resigned, was an NBA official for 13 years. He officiated 68 games in the 2005-06 season and 63 games in 2006-07, according to the Elias Sports Bureau. He also worked 20 playoff games, including five last season - Pistons-Magic on April 23; Warriors-Mavericks on April 27; Suns-Lakers on April 29; Nets-Raptors on May 4; and Spurs-Suns on May 12.

Those studying Donaghy's games might have noticed some trends.

When the home team was favored by 0-4½ points, it went 5-12 against the spread in games officiated by Donaghy this season, according to Covers.com, a Web site that tracks referee trends. Home underdogs were 1-7 against the spread when it was 5-9.5 points.

Donaghy was part of a crew working the Heat-Knicks game in New York in February when the Knicks shot 39 free throws to the Heat's eight, technical fouls were called on Heat coach Pat Riley and assistant Ron Rothstein, and the Knicks won by six. New York was favored by 4½.

Defense attorney John Lauro confirmed Donaghy is under investigation, but refused to comment on the allegations or the case.

"They are serious allegations," the leader of the referees' union, Lamell McMorris told the Philadelphia Inquirer. "It's an ongoing federal investigation. And we don't really have much more to say about it, and neither do the referees."

Donaghy is perhaps best-known previously as one of the referees in the 2004 game at Detroit that ended with Indiana Pacers players fighting with Pistons fans, among the biggest black marks in league history.

This could top it.

"We would like to assure our fans that no amount of effort, time or personnel is being spared to assist in this investigation, to bring to justice an individual who has betrayed the most sacred trust in professional sports, and to take the necessary steps to protect against this ever happening again," commissioner David Stern said in a statement.

Stern's statement said the FBI is investigating allegations a "single" referee bet on basketball. But the law enforcement official said other arrests are expected.

As if the playoff suspensions of Amare Stoudemire and Boris Diaw (in exchange for instigator Robery Horry) hadn't been a big enough miscarriage of justice, now comes news that NBA referee Tim Donaghy is under FBI investigation for betting on basketball. There are even allegations of mob ties.

While those charges have yet to be proven, there is very little debate among the basketball cognoscenti as to what was the most dubiously officiated game in this spring's playoffs. It was Game 3 of the Suns-Spurs Western Conference semifinals on May 12.

It was a bewildering carnival of bad calls, bad non-calls and egregiously late calls.

Who did that game? Eddie F. Rush, Greg Willard and Tim Donaghy.

The Suns' gut-wrenching six-game loss to the Spurs had already plunged their fans into the grief cycle, only then it was due largely to David Stern's failure to insert a measure of mitigating sanity to his zero-tolerance bench-leaving policy.

First, Game 3 will have to be put under a microscope. Hard to believe it will look any better under a jeweler's loupe than it did on TV.

Off the top of my head, the worst non-call — after Bowen forced a turnover by chopping down on Nash's off hand as the point guard was crossing over — came right in front of Rush, not Donaghy.

One other critical officiating error was a whistle on a clean block by Stoudemire, who played only 21 minutes due to foul trouble.

And then there was the whistle delivered from Shangri-La. The Suns had forced a miss, secured the ball and were pushing it up court when a foul was called, retroactive to the shot attempt. If it turns out that Donaghy made this particular call — after having a couple of seconds to think about it — it will look very bad.

The Spurs were favored by four in Game 3 and won by seven, 108-101. They shot nine more free throws than the Suns, a perfectly reasonable gap between an interior-scoring team and a jump-shooting team. While the risk of fixing a playoff game is increased by the closer scrutiny of the game, it is easier to place large bets without setting off red flags because there's much more money being wagered on a playoff game than a regular season game.

If Donaghy is convicted of fixing any games over the last two seasons — during which the FBI was monitoring his games — how will Stern, who must have precious little credibility in Phoenix, ever convince Suns fans that they weren't the victims of a fix? I mean, besides the one he himself sanctioned after Game 4. (And if it turns out Donaghy did conspire to fix Game 3, how happy will Suns fans be with the FBI for allowing their team to be an unwitting victim in a two-year-old sting operation?)

For years Stern has been dismissing the cries of conspiracy theorists and fining anyone who dared open his mouth about the officiating. He even went so far as to threaten to throw Jeff Van Gundy out of the league.

If during a criminal court proceeding it comes to light that Donaghy was influencing the outcome of games, is Stern prepared to return any fine money levied against a player, coach or owner who criticized what turned out to be crooked officiating?

Former Orlando Magic coach Brian Hill was fined $25,000 after complaining bitterly about the officiating in a game Donaghy did on March 6, 2006.

Stern could conceivably return that fine money if it turns out Donaghy was in the bag. But what if evidence emerges that Donaghy had money on the Spurs in Game 3?

If that's the case, Stern's refusal to adjudicate the Horry-Stoudemire-Diaw non-fight fairly will have compounded a criminal act. How could he ever make things right in Phoenix?

He might start by awarding Phoenix, one of the finalists, the 2009 All-Star Game. But would he dare show up?

Suns fans may still be grieving.