The sources, who spoke on condition of anonymity because grand jury proceedings by law are secret, would not say what evidence was presented.
Arenas could face charges of carrying a handgun without a license, which is a felony and punishable by up to five years behind bars. Because he has said he had four guns in the Verizon Center locker room, he faces a possible 20 years in jail. The panel also could issue a "no bill," which means that no charges are warranted.
If the grand jury decides not to charge Arenas, prosecutors could bring their own charge of possessing an unregistered firearm, a misdemeanor that carries a 12-month sentence.
But several law enforcement sources said that just because prosecutors are presenting evidence to the grand jury doesn't mean they are seeking an indictment. Often, they use the grand jury to evaluate evidence to see if there is enough for a conviction.
D.C. Attorney General Peter Nickels declined to comment on the Arenas case, but said that even if the U.S. Attorney does not prosecute Arenas, his office could file misdemeanor charges of unauthorized possession of a handgun, which also carry a one-year prison sentence and a fine. Arenas's guns were not registered in the District, making it illegal to have them at Verizon Center.
Ben Friedman, a spokesman for the U.S. Attorney's office said that nearly 40 percent of the 104 people charged in D.C. with carrying a handgun without a license received a prison sentence in 2006, the most recent year for which figures are available. About 33 percent received probation, he said. He declined to comment on the Arenas case.
The guns became an issue after Arenas and Wizards teammate Javaris Crittenton, got into an argument after a card game and Crittenton allegedly said he should shoot Arenas in his surgically repaired left knee, sources have said. Days later on Dec. 21, after a practice at Verizon Center, Arenas placed the guns on a chair next to Crittenton's locker with a note that said "pick one."
In a statement on Monday, without acknowledging the dispute with Crittenton, Arenas said he was joking and apologized to his teammates and fans. That same day, he and his attorney, Kenneth L. Wainstein, met for two hours with prosecutors and detectives. A team spokesman said Wizards General Manager Ernie Grunfeld spoke with investigators Tuesday.
Complicating Arenas's case is his 2003 misdemeanor conviction on a charge of possessing an unregistered gun during a routine traffic stop in San Francisco. Police found a .40-caliber handgun in a bag behind the driver's seat and an ammunition clip in the glove compartment. The gun was properly registered in Arizona, but not California.
Officials said a grand jury of about 24 District residents met in the second-floor, amphitheater type room at the U.S. Attorney's office and heard testimony from witnesses and reviewed evidence. The sources said the jury was not convened specifically to hear the case, but was a standing grand jury picked to hear all current cases.