LAS VEGAS — Margaret Rudin couldn't help but smile Friday morning as a witness described her as a fraud and liar.

The 57-year-old socialite, dubbed the Black Widow after she fled charges of killing her fifth husband, giggled and covered her mouth demurely as a handsome, young police officer told jurors at her murder trial how the "very, very nice" lady who reminded him of his mother managed to slip from his grasp.

"She was very cordial, very upstanding and very well-educated," the Phoenix patrolman, Officer Chris Mendez, recalled of an August 1998 encounter with Rudin a year before she was captured. "In all honesty, she seemed very sweet and very intelligent."

Rudin, who had assured Mendez her name was Ann Boatwright and she knew nothing of the murder case, beamed at the muscular 26-year-old, and he returned the grin.

"She smiled at me, so I smiled back," the officer explained later.

Despite his friendly demeanor, Mendez and another Arizona witness, the citizen who tipped police off to Rudin's presence, gave damaging testimony against her. They said she lied about her name, flashed a fake ID card to support her story, and beat a hasty exit from Phoenix within hours of her run-in with police.

"All her clothes, her make-up, all her photos, they were all left in her room," testified Vicki Drapkin, a co-worker of Rudin who called police after seeing a report on the case on America's Most Wanted.

Rudin faces life in prison for the 1994 murder of millionaire real estate developer Ron Rudin. After prosecutors convened a 1997 grand jury and seemed likely to indict, she fled Las Vegas, living in Mexico, Arizona and ultimately Massachusetts, where she was captured in November 1999.

During her four-month stint in Phoenix, Rudin lived in a YMCA and worked in the gift shop of a downtown hotel, Drapkin said. She testified that Rudin confided that her husband was dead and his relatives were trying to "cheat her out of what was rightfully hers." Drapkin, an auditor at the hotel, said Rudin even offered her $2,000 to go to Las Vegas and represent her in court.

Drapkin said she saw a stack of ID cards on Rudin's bed one day and thought it was strange, but her suspicion of Rudin was not raised until she saw the television program. She said she felt nervous and immediately contacted authorities.

Mendez said he and a partner questioned Drapkin and then tracked Rudin to the YMCA. She was "really polite," the officer said. She answered all their questions at the Y and then in a second interview the same night at the hotel. The officers tried to contact Las Vegas detectives to get a picture of Rudin, but the homicide office was closed, Mendez said. When they checked their database for arrest warrants against Rudin or Boatwright, nothing came up, he added. Several days later, he found out that there was indeed a warrant for Rudin's arrest.

When Mendez asked her if she knew Margaret Rudin, she paused for a minute and then denied it, he said. He said that when he pushed further, asking if she had killed her husband, "her reaction was calm, didn't get upset. She shook her head and said, 'I wouldn't do that.'"

Mendez said she refused to go to the police station for fingerprinting that night, but kindly agreed to go at a later date. He said her pleasantness disturbed him.

"She was laughing almost as if I had never even asked her if she had killed someone," he said.

Without any probable cause to arrest her and with other pressing police calls, Mendez sent Rudin back to Y, he testified. He said he had an "uneasy" feeling releasing her because "I thought I was talking to Margaret Rudin."

Back at the Y, Rudin ran into Drapkin.

"She said, 'Vicki, I just want you to know that I would never do anything to hurt you.' And I said, 'I believe you, Ann,'" Drapkin told jurors. It was their last conversation. When Mendez returned to speak with Rudin a third time, she was gone.

"It was an embarrassing incident for the department," the policeman admitted.

After Mendez's testimony, a female juror whose daughter has been diagnosed with cancer was dismissed from the panel and replaced with a male alternate.

Also Friday, jurors heard from Sharon Cooper, a longtime friend of Ron Rudin and a trustee of his estate. The defense had suggested the trustees were involved in the millionaire's shady business practices and his death.

Cooper said she did not even know she was named in Rudin's will until after his disappearance.

Her testimony is to continue Monday.