The health-food-store worker is now "pretty sure" the woman she saw after dark on Saturday, October 24, was not Kristine -- among other things, that woman was wearing peach-colored pants, which Kristine did not own -- but, rather, another customer "who looks a lot like her." And the Laundromat owner, who says he told his original story "to try to help," now says he does not know whether he saw Kristine on Saturday, the 24th, or Friday, the 23rd. On November 2, Rudy Persaud sat down for police questioning with his attorney. A police source says, of Rudy's November 2 interview: "Did he cooperate? Yes. Did he have an airtight alibi? No."

"There's an old movie where a guy is walking down the street under a streetlight looking at the ground. Another guy says, 'What are you looking for?' The first guy says, 'I lost my glasses.' The second guy says, 'Where did you lose 'em?' He says, 'I lost 'em over there . . . but the light's better over here.' "

Lieutenant Phillip Mahony, commanding officer of NYPD's Missing Persons Bureau, likes telling this story. His small office is dominated by metal file cabinets. Several drawers are marked patz and contain files relating to the maddeningly unsolved 1979 disappearance of 6-year-old Etan Patz in SoHo. The lost-glasses story, says Mahony, illustrates the problem with having too obvious a potential suspect: He might not be the killer.

"I can tell you this, none of the four detectives on the case think it's open-shut," he says. "This Rudy may be the guy. You certainly had a guy with a motive. He was the last one seen with her -- you can't ignore that. But it still doesn't add up. It's no crime to be the last person seen with somebody. It's no crime for a married guy to get his girlfriend pregnant. It's a shame but not a crime. You can even say, 'I have plenty of reason to want her gone,' but you're still not gonna get an arrest on it." (Repeated efforts were made by New York to contact Rudy Persaud for an interview.) Mahony says: "Our biggest fear is, she's lying in a ditch somewhere" -- the result of an accident or random mayhem -- "and we're walking by her every day because we're focusing on Rudy."

To this end, detectives combed the tracks of the D train, which she took to Baruch. They choppered low over Brooklyn and Queens and took pictures. Kristine's family and friends have also gone searching. With the help of ex-NYPD detective Gil Alba -- a specialist in solving kidnappings by Colombian and Dominican drug dealers -- and using maps of abandoned industrial sites, parks, wetlands, and isolated land near bridges (all places where bodies tend to be buried) they have gone out in small parties several times a week, talking to park personnel, harbor patrolmen, dog walkers, joggers, and vagrants. But these searches for Kristine have been futile.

Denise Lilien, now a business consultant, first met Kristine back in Madison. They were both teenagers at an alternative high school, Malcolm Shabazz -- named after Malcolm X -- which Kristine transferred to when her regular public school proved too confining. Kristine, the youngest of six Kupka children, had moved to Madison with her mother (then a factory worker) and several siblings after the death of their father, a firefighter whom Ellie had divorced. After rural Mount Carroll, Illinois, the avant-garde atmosphere of Madison, with its history of academic and political activism, suited Kristine -- as did the ultraprogressive Shabazz school, where students reclined on couches and did "free writing" exercises. Kristine went on to the University of Wisconsin, then dropped out.