Fawn Hall, unnerved by questions about her activities in the Iran-Contra scandal, burst into tears at Oliver North's trial Thursday and begged to be excused briefly as she testified against her ex-boss.

Prosecutor John Keker was asking the former secretary-turned-television personality about the events of Nov. 21, 1986, when she altered critical documents for North and helped the National Security Council staff member destroy other official papers.Hall, 29, insisted she could not recall exactly when North told her to make the alterations, then grew agitated when Keker confronted her with her own 1987 grand jury testimony with more specific information.

"I don't remember exact words!" Hall cried.

Keker asked another question and Hall tried to interrupt. U.S. District Judge Gerhard Gesell tried to quiet both lawyer and witness, but Hall kept talking and the judge scolded her.

"Please keep your mouth shut when I'm talking," Gesell said firmly. Hall paused, bit her lip, brushed away a tear and asked for a break. She fled the courtroom for 10 minutes to compose herself and then resumed her testimony.

But the tears flowed again an hour later when defense lawyer Brendan Sullivan gently asked her about her work at the White House for North and her friendship with his family.

Hall managed to say she met the North family at Easter 1983 but then bent her head and sobbed. Gesell then called for the usual 10-minute morning recess so that the witness could again calm herself.

Sullivan, who greeted Hall - "Good morning, Fawn" - asked her to describe what kind of boss North was; Hall said, "I never met a man who worked harder for his country."

Wednesday, Hall, with immunity from prosecution, told North's jury she did "a very stupid thing" when she smuggled secret documents from the White House and passed them to her just-fired boss.

She also said that four days before North was fired from the NSC staff Nov. 25, 1986, she altered original documents at his request to remove material about his secret work for the Nicaraguan Contra rebels.

While little of what Hall said was new - she gave generally the same story to the 1987 congressional committees investigating the Iran-Contra scandal - her presence generated fresh interest in North's trial, now 5weeks old.

North, a retired Marine lieutenant colonel, is charged with 12 felonies, including lying to Congress, tax fraud, destroying official documents and accepting an illegal gift. If convicted on all counts, he faces 60 years in prison and $3 million in fines.