LOS ANGELES (AP) — A visitor to San Francisco testified he heard a woman's shrill, high-pitched screams for mercy in the hallway of an apartment building where he was staying but had no idea she was being mauled to death by two dogs.

The screams he heard ultimately became a whimper, and then there was a voice saying, "Stop, please stop," David Kuenzi testified.

Kuenzi said he thought someone was being raped or beaten.

"I heard the dog barking throughout the whole thing," he said. "But it never occurred to me, nor did I have any reason to believe, that the dog was the agent of attack."

The defense called Kuenzi to bolster its theory that defendant Marjorie Knoller tried to stop the dogs from attacking 33-year-old lacrosse coach Diane Whipple.

An earlier witness, the defendants' next-door neighbor, identified Knoller's voice as the one that said, "Stop," presumably to her dog. Kuenzi was not so sure.

"I presumed it was the same woman saying, 'Stop, please stop.' It seemed the woman was no longer screaming but was begging for mercy. It was truly terrifying," Kuenzi said.

Knoller, 46, is accused of second-degree murder, involuntary manslaughter and having a mischievous dog that killed a person. Knoller's husband, Robert Noel, 60, faces the latter two charges.

Another witness, Dave Neville, testified that two weeks after the killing, he saw two dogs that looked like Presa Canarios being walked five blocks from the apartment where Whipple died. Neville said the dogs' owner gave him an unfriendly look and he turned away.

Knoller's attorney, Nedra Ruiz, later said she called the witness to try to show there might have been other dogs in the neighborhood that scared passers-by. She suggested that those who reported scary encounters with the defendants' dogs, Bane and Hera, may have been mistaken.

A series of defense witnesses have portrayed the two Presa Canarios involved in the Jan. 26, 2001, mauling death as gentle. Prosecution witnesses have told of scary run-ins with them.

Also Thursday, Judge James Warren said he would look into whether Ruiz violated a gag order by attacking the credibility of Whipple's domestic partner, Sharon Smith, during a TV interview.

He scheduled a hearing for May 17 on the matter.

Warren, who barred attorneys from commenting on the credibility of witnesses, was sent a transcript of a Fox News program interview in which Ruiz said Whipple's partner was "exaggerating or lying" about Whipple being bitten previously.

"I'm very sorry only that the judge views my actions as in violation of the court order," Ruiz said outside court.

The trial, which was moved to Los Angeles because of extensive publicity, resumes Monday.