It was just before dawn on the morning of Dec. 28, 1986 that Cara Knott's white Volkswagen was discovered abandoned in a fog-shrouded cul-de-sac east of Interstate 15 in San Diego. Her keys were in the ignition, a credit card lay on the driver's seat, her overnight gear was piled in the back. But Cara, a 20-year-old student at San Diego State University, seemed to have vanished.

The night before, shortly after 8, Cara had called home from her boyfriend's house in Escondido to say she was on her way to El Cajon, where she lived with her parents. The drive usually took 45 minutes. When she had not arrived by 10 p.m., her father, Sam, was overcome with a sense that Cara was in trouble, and he set out with his wife, Joyce, to search their daughter's usual route home along Interstate 15.

Growing edgier as midnight approached, Sam Knott flagged down a highway patrol officer and urged him to put out an all-points alert for his daughter. He was told that nothing could be done until the girl had been missing for at least 24 hours. Knott then took his distraught wife home and embarked on an anguished all-night search, crisscrossing county freeways and off-ramps, circling dark shopping malls and lonely parking lots. Additional pleas for help to police agencies proved futile. To one of Sam Knott's desperate calls, a dispatcher replied casually, "Girls will be girls."

At 5:30 a.m. Cara's sister Cynthia and brother-in-law, Bill Weick—who had also been searching through the night—decided to take another, closer look at the Mercy Road off-ramp, an uncompleted road to nowhere that led into a shadowy pit beneath the interstate. "It was foggy and dark and creepy," Weick would later testify, "like something out of a movie." Inching past construction roadblocks, they came upon Cara's abandoned VW on an isolated side road off the ramp. Numb with fatigue and fright, the couple searched the area, calling Cara's name before summoning police.

Unaware of the Weicks' discovery, Sam Knott was racing along 1-15 behind a black-and-white police car and flashing his lights in an effort to get the officer's attention. He followed the cruiser when it turned off onto the Mercy Road exit and was startled to find his daughter and son-in-law there, waiting for the police not far from Cara's car. At 8:12 a.m. one of the investigating officers peered over a bridge railing less than a mile from the car and saw Cara Knott's body in a creek bed 65 feet below. She had been strangled and thrown from the bridge.

Two questions troubled San Diego homicide lieutenant Phil Jarvis: Why had Cara Knott stopped her car that winter night—and why on a road that led nowhere? "This was one of the most intense investigations I've ever been involved with," says Jarvis, who put three times the usual number of detectives and technicians on the case. There was no sign of a struggle and no evidence that Cara-who was believed to have died between 9 and 10 p.m.—had been sexually assaulted or robbed. A computerized Chevron receipt indicated that she had refueled her car at 8:27. The VW was in working order. Detectives observed that the passenger-side door was locked and were told by her family that Knott was a careful young woman, too cautious to pick up hitchhikers. They also noted that although it had been one of the coldest nights of the year, the driver's window was partially rolled down. These clues led investigators to a chilling conclusion: Cara had stopped for someone she trusted-someone, perhaps, like a cop.

While police pressed their search, San Diego station KCST aired a spot on freeway safety featuring California highway patrolman Craig Peyer, who cautioned motorists with car trouble to stay in their vehicles. "You never know who you could meet a long the road," he said. "You could even get killed." Seventeen days after his television appearance, Craig Alan Peyer, 38, father of two and a 13-year CHP veteran with an untarnished record, was arrested and charged with the murder of Cara Knott.

Detectives had begun to focus on their own colleagues after several people came forward with tales of unusual encounters with a police officer at Mercy Road. A check of traffic citations handed out on that stretch of freeway the night of the murder turned up a ticket with the time 9:20 written in over a scratched-out 10:30. It had been issued by officer Peyer.

On the CHP force, Peyer was known as a "hot pencil," issuing as many as 250 traffic citations a month and frequently lecturing for the department on traffic safety. He had patrolled the area around Mercy Road since 1982, and after Knott's body was found, one colleague teased, "What happened, Craig, did you choke her for not signing a ticket?" None of his fellow officers seriously considered Peyer a suspect. "I couldn't believe it," said one when he heard of the arrest. "He was a dedicated officer."

Yet when Peyer's arrest was made public, more than 20 women told police he was the highway patrolman who had stopped them at the Mercy Road exit—usually for minor violations such as a burned-out taillight—and had then ordered them off the freeway. Many of the witnesses reported that Peyer had engaged them in long conversations, but none accused him of making advances.

"He just seemed like a lonely guy, bored with his shift," says one young woman whom Peyer had stopped several months before Knott's death. "He leaned against my car just making chitchat, asking me lots of questions about myself. The most flirtatious thing he said was, 'Oh, what small feet you have.' I think he liked pulling young women over and being the authority figure. He was a gentleman, but the longer he kept me down there, the more nervous I got."

Adele Tollgaard, 30, had a different impression. Peyer had stopped her on Halloween night 1986 because of a dim headlight. "He was really a nice guy," she says. "He checked my lights and my oil, so I asked him if he did windshields. He was real professional and didn't crack a smile." When Peyer discovered Tollgaard had no oil, she gladly left her car and accepted his offer of a ride home. "If the guy's innocent," says Tollgaard, who was called as a prosecution witness at Peyer's trial, "I'd hate to see him penalized for being a good Samaritan."

By that time the California Highway Patrol had already decided that Peyer's behavior was unacceptable and had fired him. The CHP findings, which turned up in the press before Peyer's trial, stated bluntly that "you did without justification cause the death of Ms. Cara Knott."

Residents of San Diego County reacted to the killing, and to Peyer's arrest, with a mixture of sorrow and outrage. But though the Knott family is convinced of Peyer's guilt, his friends and family are equally persuaded of his innocence. When Peyer was jailed following his arrest, relatives pledged their homes to secure his release on $1 million bail, and friends donated several thousand dollars to help support his family. His defenders describe Peyer as a chatty extrovert with an easy manner, often the first in his neighborhood to lend a hand when it's needed. His most ardent supporter is his third wife, Karen, who gave birth to the couple's daughter, Casey, six months before Knott's death. "Craig is not the monster these charges make him out to be," she told a local reporter. "He is the most loving, affectionate and concerned human being I've ever known."

As the case unfolded in San Diego Superior Court in January, two women working at a service station on the night of the killing testified that they had seen blood and scratch marks on Peyer's face when he pulled in for gas sometime before 10 p.m. (Four other witnesses who saw Peyer before his shift ended at 10:30 had not noticed any scratches.) A fellow officer testified that Peyer appeared disheveled and bloodied after work. Peyer told coworkers that he had slipped and fallen against a chain-link fence after refueling his patrol car at CHP headquarters.

A self-defense instructor testified that Cara Knott had been a student in his six-hour seminar in which women were taught to strike at an assailant's eyes and throat if attacked. A serologist told the court that genetic markers in a drop of blood found on Cara's boot matched markers that would be found in the blood of fewer than 1 percent of the state's population—and that Peyer is in that group. A fiber expert said that a microscopic gold thread on the victim's sweatshirt was consistent with the CHP shoulder patch on Peyer's uniform jacket. Prosecutor Joe Van Orshoven showed the jury a 46-inch nylon rope found in the trunk of Peyer's police car, which, he observed, matched the ligature marks on the victim's throat.

The jurors also heard from a succession of young women who said they had been pulled over by Peyer at the Mercy Road ramp. The night before Knott's death, Peyer had stopped Shelley Sacks, 37, and invited her into his cruiser while he wrote her a ticket for a burned-out headlight. "The whole situation was creepy," said Sacks of the 30 minutes she spent in his car. "We were sitting under the freeway, and he was talking to me about my Christmas." (Yet a young man with long, blond curls who was pulled over by Peyer testified that his encounter lasted about three minutes.)

Another witness was San Diego police patrol officer Jill Ogiivie, who said that four days after the Knott murder, she had met Peyer when he called for a backup and that he had quizzed her intensely about the Knott investigation. "When I said I thought the body had been dumped from the west side of the bridge, he said, 'No, she was put on the east side,' " Ogiivie says. "When we talked about the rumor that Knott had bitten off part of her attacker's ear, he grabbed his ears and said, 'Well, I've got both mine.' He struck me as sophomoric and juvenile." In her testimony Ogilvie said that Peyer lost his temper when she wished the murderer a slow and painful death. "He said, 'You don't know what you're talking about. It could have been an accident...maybe it just went too far.' "

A surprise witness was Michelle Martin, a former security guard, who came forward a year after Knott's killing. Pointing to Peyer, she testified that when she had seen his television spot in December of 1986 she had recognized him as the same officer she had seen stopping a "light blue VW" at the Mercy Road ramp on the night of the murder. She had notified police at the time, but no action was taken. Though Knott's car was in fact white, Martin was the only witness to place Peyer at the scene.

Peyer's court-appointed attorney, Robert Grimes, likened the circumstantial evidence in the case to a jigsaw puzzle containing hundreds of pieces that simply couldn't be made to fit. He reminded jurors that Peyer had been a model officer, and he challenged the reliability of the state's techniques for analyzing blood and fiber. He also introduced four witnesses who had seen a scruffy hitchhiker waving cash and lunging at cars on the freeway entry ramp in Escondido that Cara Knott would have taken that night. Grimes pointed out that Knott's car was discovered a half mile from the location that Peyer used to stop motorists, and the lawyer noted that six fingerprints lifted from the VW had not been identified.

The jury was divided in its deliberations on the case. "No one inferred that Peyer was mentally unstable or anything but an exemplary officer," says juror Victor Dingman. "There seemed to be no rationale for him to do something this hideous." Another juror, John Doxey, disagrees. "[Peyer] had an obsession with being a highway patrol officer," he says, "to the point that if anything got out of hand, he would see it jeopardizing the most important thing in his life."

While the jury pondered Peyer's fate, Knott's family kept an anxious vigil. At 4 p.m. on the seventh day of deliberations, Craig Peyer entered the courtroom dressed in a snug-fitting tan suit. His mother, Eileen, kept her arm around his trembling wife. Across the aisle, Joyce and Sam Knott sat with their fingers entwined.

The jurors returned looking grim and frustrated. Seven had voted for a verdict of guilty, the foreman told Judge Richard D. Huffman, while five had voted for acquittal. The deadlock could not be broken. Minutes later Judge Huffman declared a mistrial; Peyer was spirited from the courtroom through a rear corridor, while his wife exited into a blaze of television lights, wet eyed and smiling. Cara's family, stunned, remained in the courtroom, where reporters asked if they would have the strength to go through another trial. "We're tough," said a fragile-looking Joyce Knott. "We'll do it for Cara."

The off-ramp that Cara Knott took that winter night has now been blocked, and the sign that marks the Mercy Road exit is covered with plastic. Selection of a new jury was made more difficult last month when word was leaked that the defendant "attempted deception" during six polygraph tests for which he had volunteered when he became a suspect. But a new jury has now been impaneled, the trial has begun, and the fate of Craig Alan Peyer—who continues to maintain his innocence-is once more in the hands of 12 members of the public he was hired to protect.