University officials are calling on students to aid the investigation into three recent cases of graffiti containing racial slurs at Mather House.

"Nothing happens in a vacuum," Harvard University Police Chief Paul E. Johnson said yesterday. "Somebody who knows something has to come forward. That's what we're depending on right now."

The most recent racial slur, which called a specific student "a nigger", was discovered early Saturday morning in a Mather stairwell. The discovery follows two other incidents, one in which the word "nigger" was scrawled across a resident tutor's door in early November, and the other in which the words, "Die Nigger," were found above the entrance to the house weight room earlier this month.

Johnson confirmed that the department had received several calls on their Anonymous Tips Line, but "nothing substantial."

"I'm not at liberty to disclose the exact nature of the calls," Johnson said in a telephone interview.

House officials are working closely with members of the College administration in the handling of the racial incidents.

"We want to assure the community that it is being taken very seriously and firm action will be taken," said Dean of Students Archie C. Epps III.

Epps also emphasized the need for student assistance in the matter.

"We are very, dependent on other people to come forward," Epps said. "Anyone who knows anything about it, please speak to the master, the senior tutor, or myself."

While house officials are making themselves available to students who may have information regarding the incident, they are not planning to approach residents on an individual basis yet.

"We're not going to go singling out people," said Mather Co-Master Leigh G. Hafrey '73.

College officials say they plan to prosecute the person or persons responsible for the string of incidents.

"It's our intention to turn it over to the authorities as a hate crime," Epps said.

Crimes of this nature carry substantial penalties, according to Johnson. "This is a civil rights violation," he said. "It is very serious crime, whether it's handled internally or externally."

Much speculation has centered around whether the person behind the incidents is a resident of Mather.