What he said, much like many of the details of that night, remains a mystery.
Authorities provided no details of Pierce's meeting with police detectives and prosecutors at the Manhattan district attorney's office, and his attorney Michael Bachner did not immediately return telephone calls left by The Associated Press.
However, the New York Daily News reported that according to a law enforcement source, the meeting "was very productive."
"He was very forthright. He was very contrite. He said he didn't know in advance about the gun," the source told the Daily News.
Pierce practiced Friday, then changed into a white sweatsuit and left Giants Stadium in a Jeep around 1:30 p.m.
Police initially said the doctor who treated Burress after he accidentally shot himself in the right thigh at a Manhattan nightclub was to meet with authorities Friday but instead she will do so next week.
The authorities are especially interested in why neither Pierce, who drove Burress to New York-Presbyterian Hospital/Weill Cornell Medical Center, nor Dr. Josyann Abisaab called police to report the shooting. Abisaab has since been suspended for not reporting the gunshot injury, as required by law.
They also are trying to determine whether Pierce tried to cover up the shooting.
Bachner told the AP on Thursday that "he had no idea Plaxico had a weapon." But police say Pierce returned to New Jersey with Burress' gun in the glove compartment of his black Cadillac Escalade, and investigators have impounded the SUV to search it for any blood or gun residue.
"[Pierce] almost had a heart attack when the gun went off and he realized what happened," the law enforcement source said, according to the Daily News.
Pierce refused to discuss the shooting with reporters on Thursday and was not made available Friday.
He and the Giants (11-1) were focused instead on a chance to clinch the NFC East and gain a first-round bye in the playoffs with a win over the Philadelphia Eagles (6-5-1) on Sunday.
"As far as preparation, it's been business as usual," punter Jeff Feagles said. "Nothing has changed as far as the guy's attitude. There's been a little more media attention, but other than that, nothing much has changed this week."
Coach Tom Coughlin praised his team's ability to continue working.
"I think they have handled it as well as a group of young men can," he said. "They have hung together. They have tried to show care and concern. But on the other hand realize they have a job to do."
Coughlin said the Giants were not distracted last week in beating the Redskins in Washington the day after the shooting, and he did not expect it would bother his team this weekend.
Domenik Hixon, who has started the three games that Burress has missed either because of suspension or injury, will start for Burress.
The Giants suspended Burress for the final four games of the regular season on Tuesday and placed him on the non-football injury list, which will keep him out of the playoffs. But Coughlin reiterated he and the organization are still concerned for the 31-year-old receiver.
"I feel very strongly about that," Coughlin said. "And I also question anyone who would think that [the Giants should get rid of Burress]. It is just a matter of we are not going to turn our back on somebody. As I have said many times, we have tried in a lot of different ways to help him."
Information from The Associated Press was used in this report.