Tim Donaghy was in the referees' locker room at the Verizon Center in December 2006 moments before tipoff of the game between visiting Memphis and Washington.

Predicting that the Grizzlies would either win or lose by less than the eight-point spread, the NBA referee already had called in his "pick" to Thomas Martino, a longtime friend from Cardinal O'Hara High School and middleman in the short-lived gambling ring that was busted last year.

The code word he used for the visiting team was "Johnny" - the name of Martino's brother who had moved out of the Philadelphia area.

But just before the game started, federal prosecutors say, a league scorekeeper walked into the room and unwittingly provided the crooked referee with a hot betting tip. The Grizzlies, he said, were "all banged up."

Donaghy immediately called Martino on the sly and changed his pick from Memphis to Washington. All he had to say was "Chuck," the code word for the home team and the name of Martino's other brother, who still lived near Philly.

The Wizards defeated the Grizzlies, 116-101, and Donaghy pocketed $2,000 for passing the correct tip along to his gambling partners.

Two weeks earlier, he had profited from the 76ers' loss at the Wachovia Center. Donaghy, who officiated the Dec. 13 game, correctly predicted that the Celtics would cover the 3 1/2-point spread. Boston won, 101-81.

Those incidents - outlined in a letter from the U.S. Attorney's Office in Brooklyn, N.Y., that was unsealed yesterday - show how Donaghy cashed in on the inside information he had access to as an NBA ref, including officiating schedules for upcoming games and his knowledge of how referees interacted with certain players and coaches.

Prosecutors say the veteran referee, who resigned last summer and pleaded guilty to wire-fraud and gambling charges, made his predictions based on that information, and that he refrained from "intentionally" using his position to affect the outcome of games.

"There is no evidence that Donaghy ever intentionally made a particular ruling during a game in order to increase the likelihood that his gambling pick would be correct," the government stated. "He has acknowledged, however, that he compromised his objectivity as a referee because of his personal financial interest in the outcome of NBA games, and that this personal interest might have subconsciously affected his on-court performance."

In the letter, dated May 8, prosecutors detailed the extensive cooperation the Havertown native provided them and asked U.S. District Judge Carol Amon to take it into account at his July 14 sentencing.

Donaghy could receive up to 25 years imprisonment and up to a $500,000 fine, but likely will receive a much lighter sentence. His attorney, John Lauro, is asking for probation.

The feds described Donaghy's cooperation - which they said was useful in unraveling the gambling scheme involving Martino and professional gambler James "Baba'' Battista - as "significant both in its timing and its scope."

Donaghy, 41, not only dimed out his high school buddies, but also "implicated" others, including Jack Concannon, a friend who owns an insurance agency in Norwood, and Pete Ruggieri, a gambler from Glen Mills.

The government said Donaghy, who began working as a referee in 1994, had been betting on NBA games - including those he officiated - since 2003 with Concannon. Donaghy earned $10,000 to $30,000 a year betting on about 40 games a season, but lost the money gambling on football and other sports.

Concannon, a former basketball star and coach at Monsignor Bonner who was interviewed by federal investigators last year, is not expected to be charged, according to his attorney, Joseph Fioravanti. Ruggieri, whose lawyer did not return phone calls yesterday, told the Daily News last year that he would "piggyback" on bets placed by Concannon and Battista when he noticed they were winning at a 60 to 70 percent rate.

Donaghy also dished the dirt on other "NBA referees who had engaged in gambling that violated NBA rules," the government said, without providing specifics. NBA commissioner David Stern has acknowledged that some referees violated those rules by gambling in casinos, but said none engaged in criminal conduct.

In a 36-page sentencing memorandum filed last month, Lauro said that Donaghy told authorities about another NBA referee who secretly passed confidential information to a coach, and about other circumstances that affected the outcome of games and "prevented games from being played on a level playing field.'' The NBA called that allegation "a desperate act of a convicted felon.''

Assistant U.S. Attorney Jeffrey Goldberg declined to comment yesterday.

It appears unlikely that Donaghy's case will result in charges against any other individuals. Lauro recently wrote in a letter to the court that he has "been advised by the government that it has concluded its investigation in this matter.''

Martino, 42, of Marcus Hook, pleaded guilty last month to conspiring to commit wire fraud and faces 12 to 18 months in prison. The feds had been prepping Donaghy to testify against Battista, 43, of Phoenixville, but he eventually pleaded guilty to illegal gambling and is facing 10 to 16 months in jail. Both men are scheduled to be sentenced July 11.

Lauro, a former assistant U.S. attorney in Brooklyn, continued to criticize the government yesterday for approving relatively light sentences for Martino, who lied to the grand jury, and Battista, who clammed up. Meanwhile, Donaghy, who authorities say began cooperating before he was even identified as the target of the investigation, is facing a heftier sentence.

"As a former federal prosecutor in that office, the prosecutorial decisions made in this case simply make no sense,'' Lauro said in a statement. *