Federal authorities believe the referee at the center of the betting and game-fixing probe rocking the NBA will cooperate with investigators and possibly name other officials or players involved in the scandal, law-enforcement sources told the New York Daily News.

Saddled with large gambling debts, Tim Donaghy, a graduate of Cardinal O'Hara High School and Villanova University, allegedly used mobbed-up bookies to place thousands of dollars in bets on games over the last two seasons, including contests he officiated, the sources said.

Donaghy, a 13-year NBA veteran, is expected to surrender in Brooklyn Federal Court as early as today to face federal gambling charges, authorities said.

Two of the bookies are expected to be arrested this week after Donaghy surrenders, the sources said.

Investigators do not yet know if the NBA gambling scandal extends beyond Donaghy.

"Who knows what he'll say if he comes in," a law-enforcement source said.

Details of the growing scandal emerged yesterday and on Saturday and painted a troubling picture of the 40-year-old Donaghy. The so-called family man, who hid his frightening temper and shady associates from public view, has been arrested twice for erratic and threatening behavior.

In June 2002, he was charged with disorderly conduct and harassment for nearly running a U.S. postal carrier off the road after the mailman accidentally knocked over a bin of recyclables in front of the referee's home in West Chester.

Yesterday, his former neighbors in West Chester said that the NBA sicced a private investigator on Donaghy more than a year ago to investigate his gambling but let him work games all season long anyway.

Officials had the investigator question neighbors and friends of Donaghy about what they knew about his gambling habits - especially his penchant for the Borgata in Atlantic City.

The private investigator "asked, 'Does he gamble?' " said Kit Anstey, 60, a real estate agent in West Chester. "I said, 'Yes.' "

Anstey told the investigator - who said she worked for a local firm hired by the NBA - that Donaghy bet on golf games, neighborhood poker games, and at an Atlantic City casino.

The prober never asked Anstey whether Donaghy bet on pro basketball games.

"It was about his gambling habits," said Anstey, who once helped the referee buy a $500,000 home.

"The NBA knew about his gambling," said former neighbor Pete Mansueto. "A lot of people were talking about it."

The NBA refused to comment on the probe and said commissioner David Stern would speak publicly this week.

As for the charge in June, 2002, "He was pretty nasty," mail carrier Charles Brogan, 48, said as he recalled trying to make a delivery at Donaghy's house in West Goshen, Chester County.

As Brogan attempted to drive his route, a screaming Donaghy chased him by hopping into his car and speeding after the postal truck, Brogan said.

"He kept cutting me off," said Brogan, adding that Donaghy narrowly avoided ramming his truck several times.

Donaghy later came to the post office to apologize at least three times, but Brogan said he refused to talk to him. The criminal case was dropped because Brogan failed to show up for a court hearing.

Donaghy's longtime caddie at the Radley Run Country Club in West Chester - which suspended the referee in 2004 for bad behavior - said the NBA referee ruffled feathers there as well.

"A lot of people felt he was rude," said Brent Devantier, 23.

Donaghy, who now lives in Bradenton, Fla., also was sued in 2005 by a neighbor in West Chester, where he moved from West Goshen, for instigating "a pattern of public harassment," according to court papers.

Sources told the Daily News that federal authorities first heard Donaghy's name on a wiretap during investigations into the Gambino crime family over the last year.

A Philadelphia mob figure is believed to have threatened to use his contacts in the Gambino family to hurt Donaghy if the referee - already known as a heavy gambler - did not share inside information and help fix games, sources said.

That gangster also claimed he would expose Donaghy's serious debts if he did not cooperate with the bookies.