It was Marjorie Knoller the witness who doomed Marjorie Knoller the murder defendant, coming across as unbelievable and unsympathetic in the trial for which she was found guilty for the dog-mauling death of her San Francisco neighbor.

Knoller on Thursday became the third person in the U.S. convicted of murder in a dog-mauling case. One of her massive Presa Canario dogs, which weighed 120 pounds, ripped open 33-year-old Diane Whipple's throat while the other ripped off the victim's clothing in an apartment-complex hallway.

Prosecutors said the victim, a 110-pound college lacrosse coach, had been bitten everywhere except the top of her head and the soles of her feet. 

Knoller was convicted of second-degree murder, manslaughter and having a mischievous dog that killed someone. Her husband, Robert Noel, was found guilty of the two lesser charges. He was not charged with murder because he was not at home during the attacks.

The murder charge could send Knoller to prison for 15 years to life. Each of the lesser charges carries a sentence of up to four years.

"There's no real joy in this but certainly some measure of justice for Diane was done today," Whipple's domestic partner, Sharon Smith, said later. "I'm glad to see the jury didn't buy some of the smoke screens that were put in front of them." 

After the verdict, jurors said they thought Knoller, 46, and Noel, 60, had been "arrogant" to ignore warnings from more than 30 people that their dogs, Bane and Hera, were dangerous.

In all, the seven men and five women who served as jurors deliberated for 11½ hours over three days before convicting the couple. They decided the most serious second degree-murder charge last. 

"It was a painful decision," Newton said. "The question of implied malice was a difficult question to decide, but we did decide there was implied malice in her actions." 

He said Noel, who was not present during the attack, nevertheless "was equally responsible." 

Jurors said Knoller was unbelievable as a witness. They also said Noel, whose letters about the dogs were admitted as evidence, "doesn't seem to be a very nice person." 

Even so, juror Shawn Antonio, 27, said the panel resisted making a decision based on personalities, carefully weighing the evidence instead. 

The jurors, who met with reporters after the verdict, said Knoller's situation was worsened by the behavior of her flamboyant lawyer, Nedra Ruiz. 

Ruiz, who was admonished by the judge for interrupting the prosecutor during his closing argument, had crawled on the floor, kicked the jury box and cried during her opening statement.

"She's an amazingly dramatic person," jury foreman Don Newton, 64, said. "She's an incredible actress and I think to some extent she was counterproductive."

Also helping jurors reach their decision was a TV interview prosecutors repeatedly showed in which the couple disavowed responsibility for Whipple's death and appeared to blame the victim. 

"It's not my fault," Knoller said in the interview. "Ms. Whipple had ample opportunity to move into her apartment. She could have just slammed the door shut. I would have." 

Antonio said that had a powerful impact on him and on other jurors. 

"There was no kind of sympathy, no kind of apologies," he said. "It helped us a lot." 

The defense lawyers, Ruiz and Bruce Hotchkiss, contended that Knoller and Noel could not have known their animals would kill, and that Knoller tried to save Whipple by throwing herself between her neighbor and the enraged Bane. They also disputed witnesses' accounts of being menaced previously by Bane and Hera.

Loyola University Law Professor Laurie Levenson gave high marks to the prosecutors, Assistant District Attorneys Jim Hammer and Kimberly Guilfoyle-Newsome. They set out to prove that the husband-and-wife lawyers knew their two powerful Presa Canarios were "time bombs." 

"We've gotten so used to TV trials we forget how important evidence is and how competently it is presented," said Levenson. "Lawyers sometimes get distracted from their mission. The prosecutors kept their eye on the prize." 

Sentencing was set for May 10 in San Francisco. The case had been moved to Los Angeles because of heavy pretrial publicity. 

The Jan. 26, 2001, attack had seemed too bizarre to be real at times and quickly generated much attention.

The owners were lawyers who specialized in lawsuits on behalf of inmates. They had adopted an inmate, white-supremacist gang member Paul Schneider, who officials said was trying to run a business raising Presa Canarios for use as guard dogs. The prosecutor alleged during pretrial hearings that Knoller and Noel practiced bestiality with their dogs. Evidence relating to that claim was barred from the trial. 

On the other side of the aisle, Whipple's partner, Smith, made legal history before the trial even began when she claimed the same right as a spouse to sue for damages. The state Legislature enacted a law to allow such lawsuits by gay partners. 

Levenson said Thursday's verdict was likely to send a message across the nation. 

"This does not mean that every dog mauling case will end up as a murder case," Levenson said. "But it does mean if people have prior warning they will have to take it seriously."

The Associated Press contributed to this report.