By Dree deClamecy
CNN Producer

LOS ANGELES (CNN) — The couple whose dogs mauled their neighbor should be held accountable for the savage attack "because they killed Diane," the victim's domestic partner testified Thursday.

"It was their dogs and their careless disregard for Diane's life that caused her death," a tearful Sharon Smith said of Robert Noel and Marjorie Knoller, the married couple who are on trial for the death of Diane Whipple, 33.

"I believe they are guilty and responsible for taking Diane's life, and I want to make sure they are held accountable."

On the day of the attack, January 26, 2001, she said Whipple had called her at work, urging her to come home early so they could go to the movies.

When she got to the apartment, around 5:30 p.m., police and emergency crews were everywhere. She couldn't enter the building because police had sealed off the entrance with crime scene tape.

"My landlord was in front and she told me what happened," she said.

Whipple later died at the hospital, with Smith at her side.

The testimony was the most powerful since the trial began last week, with friends of Whipple and Smith crowding the courtroom. Many in the courtroom cried during the testimony, others intently watched and listened with their arms wrapped around the shoulder of the person next to them.

Noel glanced at Smith while she testified, but Knoller looked away, much as she has done when others have testified.

At one point, Whipple's shredded, blood-stained clothes were displayed in court. Her jeans and sweater were torn into such small pieces it resembled shredded lettuce.

"The clothing is basically shredded, in very poor condition, ripped to pieces," said Spencer Gregory, a crime scene investigator with the San Francisco Police Department.

Smith, who referred to Whipple as "my life partner," said she and Whipple had at least two encounters with the dogs before the day of the fatal attack. In conversations, they would refer to the animals as "those dogs" and Noel and Knoller as "those people."

On one occasion, she said one of the dogs came at her very fast, and she stuck her hand out in a friendly gesture. "No, don't do that," she quoted Noel as saying.

Another time, in December 2000, she said Whipple called her up at work and said, "That dog just bit me."

Smith testified that Whipple later told her the dog bit her left hand as she was leaving the apartment building and Noel was bringing the dog inside.

"You need to control your dog," she quoted Whipple as telling Noel, who stared at her without uttering a word.

However, Smith said they did not file a complaint with the apartment manager and instead just tried to avoid the dogs. But the incident had clearly rattled Whipple.

"She was very scared of those dogs," Smith said.

Under cross-examination, defense attorney Nedra Ruiz pressed Smith on why a complaint was never filed: "Have you considered that if you had made a complaint, Ms. Whipple would be alive today?"

That question drew an audible gasp from the gallery. At least one woman wiped away tears. The prosecution objected and the judge sustained the objection.

Moments later, Ruiz asked Smith about a civil suit she has filed against Noel and Knoller seeking damages -- a move that opened the door for the prosecution to ask her about why she felt the couple should be punished.

Why do you believe they are responsible, asked lead prosecutor Jim Hammer.

"Because it was their dogs and their careless disregard for Diane's life that caused her death," Smith said.

Knoller and Noel have pleaded innocent to the charges of involuntary manslaughter and keeping a mischievous animal that killed a human being.

Knoller -- who was with the two, large Presa Canario dogs during the attack on Whipple -- was also charged with second-degree murder.

Whipple, returning home with groceries, had the key in her door and one of two bags inside when the attack began.