The first threats came via e-mail more than a year ago -- racist insults spewed at 61 high-achieving minority students at Penn State University. Last fall, hateful letters were sent to three black students and an African American member of the board of trustees.

Soon, there was a second round of letters, one warning the university's most visible African American student leader, LaKeisha Wolf, that her time was "up." Late last month, the threats became even more pointed.

"Don't you realize that I could have killed you 10 times by now -- your monkey boy bodyguards notwithstanding," said the letter to Wolf, president of the university's Black Caucus. It added that authorities should scour Mount Nittany, which overlooks the Penn State campus here, for the body of a young black man.

On a campus where even the president admits that racial incidents are not uncommon, the latest round of hate mail prompted a multiracial group of 300 students to stage a sit-in in the student union April 24. They remained there as of Tuesday, angry with what they called the university's lackadaisical response to the situation.

Three days earlier, 26 students were arrested in front of 40,000 fans when they interrupted the annual Blue-White football scrimmage to call attention to the racial problems on campus.

"When you read the letters, you hear the very same sentiments that you hear around here every single day," said Wolf, who was given a 24-hour guard by the university. "We realize that this is a problem of ignorance that the university must address."

In a development that has only added to the tension, a woman walking her dog discovered the body of a black man on a roadside in Bradford County, about 100 miles from here, after three days of police searches of Mount Nittany came up empty. Last Friday, the body of a second black man, a 38-year-old New Yorker, was found in Centre County, about 20 miles from campus.

Police and university officials say neither victim has any connection with Penn State or the mailed threats. State police and the FBI continue to investigate the threats, which they say have yielded few clues beyond the postmark from a huge mail processing facility in Altoona, Pa.

Students say that even before the current crisis, slights, insults and even assaults directed at black and other minority students were commonplace.

Earlier this year, assailants pelted a group of black students with rocks from the roof of a building on campus. Students insist that the incident was racial, though university officials say a black student was among the three assailants.

Black students say they have been shut out of fraternity parties by hostile white hosts who said black students are not allowed. Others complain that they are forced to endure the grumbling of white students who seem perplexed -- and even angered -- by their grievances.

"The biggest problem we have at the university is not as much the highly visible incidents where a crime has been committed, such as with these threats," said University President Graham B. Spanier, who heads a campus where 3.6 percent of the 41,000 students are black. "We have in a given year hundreds of incidents where people are making racist comments, being insensitive or telling racist jokes.

"These are not necessarily the kinds of things that would add up to a hate crime, but for a minority student, they add up and create a sense of exclusion and hostility."

Many of the hate letters sent to students also make reference to Penn State's football team, a traditional powerhouse that last year suffered its first losing season in decades. Students say it is not unusual for black players to date white women, something that stokes the anger of some whites.

Several football players have received hate letters, according to university officials.

Last week, a black music student received two death threats: one left at his school and another slipped under the door of his apartment.

The threats have added to a sense of isolation that black students say is fostered by the university's location in central Pennsylvania's Happy Valley, a bucolic region that is overwhelmingly white and largely peaceful -- but one that is also considered a hotbed of organized hate group activity. Spanier, who is Jewish, says he has received anti-Semitic mail during his six years at the helm of the university.

"Some of it is vile," he said. "Our society is still grappling with racism, and universities are microcosms of the larger society."

As students take final exams, protest leaders have been holed up behind the locked doors of the union building's Paul Robeson Cultural Center. Supporters in a lounge area are sprawled on comforters and pillows, listening to music, reading and eating food donated by local businesses. They have vowed to stay until university officials do more to address the racial animosity on campus.

They want the university to add staff to its African and African American Studies department. They are also demanding that the university require all students to take two courses in race relations and that the academic officer in charge of diversity issues be given control over 2 percent of the university's budget -- or about $42 million -- to ensure that his initiatives are carried out.

So far, Penn State officials have agreed to several elements of the plan, including funding new teaching slots in African and African American studies and strengthening course requirements in race relations.

But officials refuse to alter budgetary authority or grant academic amnesty to students who are missing final course work because of the protest. They say their hope is that the students will go home when the university effectively shuts down after May 12 graduation exercises.

Students and supporters protesting racial threats at Penn State University are encamped in the student union. They have vowed to stay until officials do more to address the situation.