When spring-term classes began at Indiana University last January, Murray Sperber was understandably on edge. Sperber has taught English and American studies at the university for nearly three decades, and until recently his life followed the generally peaceful contours of a scholarly existence. Dropping in on one of his classes, one might find him analyzing the language in Arthur Miller's Death of a Salesman or discussing the social impact of Jack Kerouac's On the Road. Owing to his role in a recent campus controversy, however, Sperber has lately been feeling less like a professor of literature than like a man on a hit list.

On the advice of campus security, Sperber carries a cell phone programmed to contact the police at the touch of a single button. He was urged to enroll in a self-defense course at the local police academy (he is taking judo) and was also trained by the police in "verbal judo"—methods for defusing verbal confrontations so that they don't turn into physical ones. He was advised to avoid letting his whereabouts be known. His spring-term courses—one on post-World War II American literature, and one on the modern media—were listed in the university catalogue under other faculty members' names. (Students who enrolled were baffled on the first day of class by the sight of him; many thought they had misread the room number.) Sperber declines to hold office hours and will meet with students only in public places.

Sperber's troubles began on March 15 of last year, when he appeared on a CNN/Sports Illustrated television exposé about Bobby Knight, the legendary basketball coach whose success on the court (three National Collegiate Athletic Association championships and eleven Big Ten titles since joining Indiana University, in 1971) had led virtually everyone at the school to overlook his tyrannical behavior. But Sperber also happens to be one of the country's most outspoken critics of college sports, a subject he has examined in several books. So he had welcomed the opportunity to speak to CNN/SI about the now famous complaints about Knight: that he had a penchant for wild, expletive-filled tirades, and that he had once tried to choke a player.

Asked what would happen if he himself were to behave this way in a classroom, Sperber said that he would almost certainly lose his tenure. What would happen to Knight? Bobby Knight was "the emperor of Indiana," Sperber replied; no one would hold him accountable. Indeed, the day before, Indiana University had held a press conference to defend Knight in advance.

In Indiana, of course, few things are taken more seriously than basketball, and Sperber's remarks constituted a transgression that many considered unforgivable. The following morning he awoke to a torrent of irate and obscene telephone calls and e-mails. "Shame on you for giving such a wonderful university a black eye ... You should resign!" read one e-mail, from an Indiana University alumnus. "You are a vile and pathetic little worm," another said. Anonymous callers flooded Sperber's answering machine with vituperative messages. Disparaging letters began appearing in the local paper.

Initially, Sperber was right about Bobby Knight's inviolability. Even after CNN/SI obtained and aired footage of the choking incident, the university allowed Knight to keep his job, although it fined him $30,000, suspended him for three games, and imposed a "zero tolerance" policy with respect to any future incidents. Sperber continued to speak out on the issue, and the angry missives from Indiana fans took on an increasingly threatening tone. "If you don't shut up, I'll shut you up," one caller warned. Sperber soon noticed that the schedule for his fall classes had been posted on a Web site for Indiana University basketball fans. "I see dead bodies," a heading on the site declared; it was followed by a list that included Sperber's name and those of two newspaper columnists who had also been critical of Knight.

Strangers began approaching Sperber in supermarkets and coffee shops and warning him to stop talking about Knight. Others shouted at him as they drove by his house or passed him on the street. "You're that fucking professor who won't keep his mouth shut!" a student yelled from across a parking lot one day; Sperber changed direction in order to avoid a physical confrontation. Another man rolled down his car window and swore at Sperber as he stood on a street corner with his ten-year-old foster daughter, waiting for the light to change. Sperber began fearing for the safety of his family. They stopped going to restaurants, tired of the icy, intimidating glares they drew from other diners. His wife stopped using her credit card after a store clerk, recognizing her last name, verbally harassed her.

Sperber started having nightmares and losing sleep. He could barely concentrate on his work. Arriving at his office one day, he was greeted by a message on his answering machine from a man who listed the days and times of Sperber's classes and warned, "I know how to find you." The campus police offered to post an armed guard in Sperber's lecture rooms. But, exhausted by the threats and the pressure, and feeling that he could not teach under such conditions, Sperber decided to take an unpaid leave. On June 20 he left Bloomington for Montreal, where he was born and raised, and where nobody much cared about Bobby Knight.

A few months ago I met Sperber for dinner in Bloomington. He was back because Knight was gone: last September, after Knight upbraided a student and committed other violations, he was fired. (He has since been hired by Texas Tech University.) His dismissal sparked an uproar on campus, but that eventually died down, and Sperber decided it was more or less safe to return.

When we got together, he seemed relieved by Knight's departure but was visibly worn by events. "The die-hard Knight fans are still out there," he told me wearily. "They still post messages whenever I speak publicly." Several times each day he logs onto various Indiana-fan Web sites to see if any new threats have been posted. "There were some denunciations today," he said. "The usual low-level 'I hate this guy, why doesn't he shut up?'"

Dressed in jeans, sneakers, and a San Francisco 49ers cap, Sperber looked nothing like the pointy-headed professor his critics often portray him as. Before becoming a professor he spent two years playing semi-professional basketball in Europe, and although an injured knee has kept him off the courts for years, he remains a fairly avid sports fan. He began writing about college athletics because of an interest in NCAA soccer.

Not surprisingly, however, Sperber's investigations of amateur athletics and especially the past year's experience have given him a somewhat jaundiced view of college sports. Again and again over the past year, he told me, people e-mailed or called him to ask, "Don't you understand that the purpose of Indiana University is the basketball team? That's what pays your salary as an English teacher!"

In fact, as Sperber points out in his latest book, Beer and Circus: How Big-Time College Sports Is Crippling Undergraduate Education (2000), the vast majority of athletic programs actually lose money, because expenditures for equipment, facilities, and travel generally outstrip revenues from ticket sales and TV contracts. Although a few universities have seen enrollment rise following athletic success, Sperber argues that the disproportionate focus on college sports is partly responsible for swelling class sizes and a declining emphasis on undergraduate education. A graduate of Purdue University, where, he says, he obtained an excellent education forty years ago, Sperber believes that the problem is particularly bad at public universities, where the beer-soaked, sports-oriented party scene prevails.

Some fellow critics of college sports would debate this proposition. In their provocative book The Game of Life: College Sports and Educational Values (2001), James Shulman and William Bowen argue that the impact of sports is in some ways greater at Ivy League universities and small liberal-arts schools, where the proportion of athletes in the student population is higher than at big public universities. Sperber is unconvinced. At schools like Swarthmore and Williams, he says, most students still receive a quality education, and sports do not play a remotely comparable role in shaping the culture.

The day after our dinner I sat in on one of Sperber's classes. Toward the end he left the room, and the conversation turned to his situation. Several students told me that their friends still express horror at even the mention of their professor's name. A few admitted that at the start of the semester they had shared this reaction and had considered dropping the course. (Only one student actually did so.) But for all his public outspokenness, the students said, Sperber almost never mentioned Knight or his own role in the controversy during class. They seemed to appreciate this. They had come to think of Sperber not as Bobby Knight's critic but as an ordinary professor—which is, of course, what he is hoping to become once again.