NBA referee Tim Donaghy is under investigation by the FBI for allegations that he bet on games that he officiated over the past two seasons and that he made calls affecting the point spread in games, multiple sources told ESPN.
Donaghy, a 13-year veteran of the league, is aware of the investigation and resigned from the NBA recently.
The NBA issued a brief statement Friday, saying: "We have been asked by the FBI, with whom we are working closely, not to comment on this matter at this time."
According to a law enforcement official, authorities are examining whether Donaghy -- whose identity was not revealed until Friday afternoon -- made calls to affect the point spread in games on which he or associates had wagered.
The law enforcement official, who spoke to The Associated Press on Friday on condition of anonymity, said the referee was aware of the investigation and had made arrangements to surrender as early as next week to face charges. The official, who did not identify the referee, is familiar with the investigation but was not authorized to speak publicly about the ongoing investigation.
The investigation first was reported Friday by the New York Post.
The law enforcement official said the bets involved thousands of dollars and were made on games during the 2005-2006 and 2006-2007 seasons.
The FBI probe, which began recently, also involves allegations that the referee had connections to organized crime associates. Other arrests are expected, the official said.
The referee had a gambling problem, according to the official, and was approached by low-level mob associates through an acquaintance.
Nevada gambling regulators were not involved in an investigation and had no information about the allegations, said Jerry Markling, enforcement chief for the state Gaming Commission and Gaming Control Board.
Jay Kornegay, executive director of the sports book at the Las Vegas Hilton, said he had never seen any unusual activity in NBA betting, and was surprised not to have heard about an investigation until Friday.
"Whispers would have happened on the street, and we would have heard something," Kornegay said. "Any type of suspicious or unusual movements, you usually hear in the industry. We're so regulated and policed, any kind of suspicion would be discussed.
"We haven't seen anything like that in the NBA that I can remember," he said, "and we haven't been contacted by anybody."
Kornegay said legal sports betting in Nevada represents a fraction of sports betting worldwide, with 98.5 percent of all action taken outside the state. Clayton cited a 2005 estimate by the National Gambling Impact Study Commission that found $380 billion is wagered on illegal sports betting, compared with $2.25 billion in legal sports betting in Nevada.
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.
NBA commissioner David Stern had long objected to putting a team in Las Vegas because it permits betting on basketball, though earlier this year allowed Mayor Oscar Goodman to submit a proposal to owners on how the city would handle wagering on a team if it moved there.
Information from The Associated Press was used in this report.