Capping perhaps the worst week for the defense to date, a neighbor of O.J. Simpson testified Friday that the defendant's white Bronco was not in front of his house on the evening he allegedly committed two murders.

Charles Cale, a surprise witness who said he was walking his dog that fateful night, bolstered an account given a few days earlier by Allan Park, a limousine driver who said he did not see the Bronco where police found it the next morning, outside a gate of Simp son's estate.While the defense managed to get Park to concede he could not be absolutely certain about his memory, Cale did not waver a moment. "I'm very certain," he told prosecutor Marcia Clark.

If the jury accepts the two men's recollections - and they both seemed credible, despite persistent defense attempts to undermine them - it puts a dent in Simpson's alibi. Several legal analysts used words such as "devastating" to describe the possible impact.

Simpson's lawyers have repeatedly said the former football star was home at the purported time of the killings, while prosecutors assert he used his Bronco to drive to the murder scene. The accused has pleaded not guilty to the grisly slayings of Nicole Brown Simpson, the defendant's ex-wife, and her friend Ronald Goldman last June 12.

Brian "Kato" Kaelin, who lived in a guest house on Simpson's property, has said the two men returned from a trip to McDonald's restaurant at about 9:35 p.m., or 40 to 45 minutes before the killings allegedly occurred a short drive away.

Cale said he walked his dog by the area between 9:30 and 9:45 that night, and did not see the Bronco. He added that it was parked there at 7 the next morning, when he rode by on the way to the airport.

"I was surprised to see it," said Cale, who described himself as an investor. "I noticed that it was parked at sort of a strange angle. Also, I had not noticed it . . . the prior evening."

Robert Shapiro, who handled the cross-examination, tried to get Cale to say he was unsure about either his timing or his observation, but the witness would not be swayed. Shapiro also tried to suggest a dark motive for Cale emerging belatedly and avoiding discussions with the defense so it could prepare for questioning.

Cale's court appearance came as a surprise to most observers because prosecutors never mentioned him publicly before, but he evidently was interviewed by police and subpoenaed by prosecutors two months ago, so the question appeared to be why Simpson's team did not contact him sooner.

Shapiro implied that Cale tried to evade him by not responding to a phone message Thursday night. The witness said he had been ill and did not know the call was urgent.

Though the matter wasn't addressed in court, Cale reportedly came forward after he heard testimony from Rosa Lopez, a maid who worked next door to Simpson and said she saw the Bronco during the critical time frame. Lopez' testimony was videotaped, but it was so riddled with problems that it is unclear whether the defense will ever play it for the jury.

It is too soon to assess how badly Simpson's side has been hurt by the latest testimony, because it has yet to present its case.