Frustration of a different sort plagues authorities in missing-persons cases. Without a body, it is extremely hard to prove that a crime has even been committed. Prime examples are the recent indictment of grifters Kenneth and Sante Kimes for the murder of heiress Irene Silverman, and the indictment, in November 1997, of prominent Delaware attorney Thomas Capano for the June 1996 murder of governor's assistant Anne Marie Fahey. In both cases, police had early circumstantial evidence that pointed to the suspects. But the absence of a body made securing indictments extremely arduous. In the Kupka case, the police still aren't certain that a homicide has been committed.

By early December, the number of detectives working on the case had shrunk to four; by mid-December, to just two. Today, ten and a half weeks after Kristine's disappearance, the identity of the Baruch College teacher who left with her that morning is still being kept secret by the nervous college and the proprietary Police Department. Kristine Kupka's family and friends, convinced her fate lies in his hands, believe it is time to change that.

The man who accompanied Kristine on her October 24 outing is Darshanand Persaud; most people call him Rudy. Persaud is a respectable young Indo-Guyanese-American. A 1995 graduate of Baruch, a Manhattan-based branch of CUNY, he was a quality-control chemist who tests glue products at Basic Adhesives, in Brooklyn, and an adjunct lab instructor at his alma mater. He currently attends the New Jersey Dental School in Newark, making a cumbersome commute (subway to PATH train to school bus) to get there each morning. He is now married to an accountant in the Dreyfus Corporation's Park Avenue office; the couple live with his parents in a neat house in a rundown section of Brooklyn. He's the family's only son; the oldest of his three sisters is a physician.

Miguel Santos, the lecturing professor for Introduction to Environmental Sciences, whose lab sections Persaud taught, found him "a very pleasant, cordial, nice person, knowledgeable in science and a good teacher." Students characterized him as handsome, sometimes polite, sometimes angry and moody. He was decorous; he had refrained from dating Kristine, his student, until he had filed her course grade. It was Kristine -- with her long, black clothes, bright-red hair, extra-strength opinions -- who had flirted with him. When Kristine's classmate Anthon Grant, a 26-year-old Trinidadian who had befriended Persaud on the basis of their mutual interest in computers and shared Caribbean background, told him last May that he thought Kristine had a crush on him, "Rudy said, 'Come ahhhhn. . . .' "

Kristine found Persaud's shyness charming. "She thought of him as this gentle-lamb sort of guy, honest and naïve," says Michael Legatt, a fellow member of Kristine's in Baruch's Philosophy Club. Indeed, Persaud's clean-cut looks and slight awkwardness led her to compare him, to several friends, to "a newborn baby."

Where Kristine saw guilelessness, Anthon Grant saw calculation. "Rudy was very GQ-ish. He never had a bad-hair day. He seemed like someone who had his own agenda -- like his main goal was getting ahead in life, like he didn't want to be where he was, that's for sure. He would walk into class late, in a trench coat, like he'd just come from someplace important." He was "Mr. Persaud" to his students, who were mainly his age, and when the class first overheard Dr. Santos address him informally, "we looked at each other, like, 'Rudy'!?" Grant says, laughing. It seemed too goofy a name for Persaud.