The Nicaraguan contra who was pelted with eggs and fake blood when he visited April 2 will return to speak again at Harvard tonight amid beefed-up security, but non-undergraduates will be excluded from hearing him.

Dean of Students Archie C. Epps III said he decided not to allow graduate students and non-Harvard affiliates at the event because he had to be "absolutely certain" that the members of the audience "understood the importance of free speech. "I can't have that assurance with . . . graduate students" or any non-members of the Harvard community, Epps said last night.

Other measures to prevent interruptions during the talk will include an "overwhelming police presence at the speech--overwhelming," said Saied Kashani '86, president of the Conservative Club, which is sponsoring the speech. Epps refused to give details about security.

Kashani said the Conservative Club invited the controversial Jorge Rosales to return to Harvard because President Derek C. Bok promised the club that if "Rosales came back, he would be heard. We're holding the University to that promise." The other speaker at the 8 p.m. Science Center event will be Maria Gonzalez, a native of El Salvador who is also opposed to the Sandinista government in Nicaragua.

Rosales, a spokesman for the Nicaraguan Democratic Force, was hit with eggs and blood-like liquid after only three sentences of his speech in Boylston Auditorium last month.

Graduate students active in Central American politics said they are upset that they have been excluded from the event. "It makes me angry," said Douglas M. Brugge, who is a member of theCommittee on Central America (COCA) and a graduatestudent in Biology.

"Some of us have offices in that very buildingand [we] find it unreasonable that we're notallowed to attend the program," Brugge said.

In a meeting at the shanties in the Yard lastnight, COCA voted to protest Rosales' presence byreading selections from a book which they say willcontradict the statements of the Contra. Inaddition, COCA will have pickets and "unitingchants" before the speech, Brugge said.

But COCA voted to denounce the position oftrying to prevent Rosales from speaking at theevent, which will be held at 8 pm. Andre Weltman'86, a member of a Trotskyist group, dissentedfrom the decision, saying, "God damn it, we shouldkeep these butchers on the run. These same guysare the guys who, when they catch you, want torape you or [sexually mutilate you]."

Other students suggested moderation, suggestingthat COCA allow intellectualism to prevail overemotionalism. "I have a sense of moral andintellectual superiority over this guy and I don'tsee how [being emotional] about this issue couldhelp us," said Jason Ravitz '88