Some rookies break in the hard way. But few have faced a tougher baptism of fire than pretty, raven-haired Janey Jimenez. Barely two hours after her swearing-in, the deputy U.S. marshal drew the duty of a lifetime. Her assignment: guard Patty Hearst.

That was in September 1975, just 11 days after the FBI's capture of the fugitive heiress in a San Francisco apartment. Taking a handcuffed Patty to a nearby hospital, Janey watched her weeping during a gynecological exam. "I had never seen anyone so beaten, crumpled, totally helpless," she has recalled. "She lay without moving...eyes vacant, curled up like a fetus." When the doctor left, Patty started to sob again, and Janey cradled her head in her arms. Such solicitude went beyond the call of duty, she concedes, but no matter: "She was another human being, a woman and a contemporary in distress. I had to let her know she was not alone."

Jimenez, now 24, resigned from the marshal service shortly after Patty's conviction on federal bank robbery charges. Her book, My Prisoner, will be published next month. It is a sympathetic, highly personal portrait of a troubled and confusing young woman. Writes Janey: "Patty laughs easily, weeps when she is hurt, is quick to sympathy, and almost fanatic about fairness." Jimenez still sees many of the jurors who found Patty guilty, and reports that most have reconsidered their verdict. "Nearly all," she says, "are haunted by the nagging intuition that if Patty had been presented to them more clearly, as a recognizable person rather than an enigma, they would have acquitted her."

But lawyer Al Johnson, writes Janey, exerted a smothering influence over Patty in court; he ordered her not to smile and coached her incessantly on how to wear her hair, trim her nails and modulate her voice. "He seemed determined to control every move she made," Jimenez observes. Head defense lawyer F. Lee Bailey is viewed more favorably in the book, but Janey lately has been having misgivings. "In the beginning Bailey was so good," she says now. "But toward the end it was like he didn't care. In the closing argument he was nervous, and he didn't go over a lot of details that the jury told me later they thought he should have. And they also noticed when he was fumbling and spilled his water."

With Patty free on $1.5 million bail, Janey has been a guest of the Hearsts several times. Patty, she reports, is taking a course in real estate, and swimming and playing tennis at her parents' country club, lunching with girlfriends and dating friends of the family. Twice, Janey says, she fixed Patty up and they double-dated at discotheques, but Patty's interest was constantly wandering. Often, says her friend, "she seemed to be staring off into the wild blue yonder. One minute she would be with you, the next she was gone. It was like she was dead for a minute, then she'd come alive again."

Jimenez, now studying criminology at San Diego State University, will go on tour to promote her book in October. As for Patty, she says simply, "I hope her nightmare will end someday. I don't know if it's possible, but I hope she'll always be as strong as she is, and that she will stop waking up nights reliving the whole episode over and over." Will the Jimenez-Hearst friendship endure? "Yes," Janey says firmly. "I can trust Patty and tell her things. But she is easily influenced by people and can be made to act like a puppet sometimes. I hope it won't be that way always."