Protesters camped outside the office of Duke University's president for a fourth day Monday, demanding the firing of three administrators -- including one accused of using a racial slur against a parking attendant -- and calling for a $15 minimum wage for all campus workers.

President Richard Brodhead met Sunday with the protesters, who are occupying his office's waiting room inside the building that houses his office and those of other top administrators. Nine students have been there since Friday afternoon. On Monday, the protesters remained in Allen Building, which is closed to the public, Duke spokesman Keith Lawrence said.

Another spokesman, Michael Schoenfeld, initially said officials told the students they would face criminal trespassing charges, academic sanctions or both if they didn't leave Sunday. But just before midnight, the school issued a statement saying that "in order to facilitate productive dialogue and move towards a peaceful resolution," the protesters would not be subject to student conduct sanctions or legal penalties.

The statement said discussions would continue Monday.

Among the administrators the protesters want fired is a top executive who was involved in a dispute with a parking attendant two years ago. A lawsuit filed last month by the contract traffic control officer accuses Duke executive vice president Tallman Trask III of using a racial slur against her.

Trask has said parking attendant Shelvia Underwood refused to let him park in his usual spot and stepped in front of his car. He denied making any racial comment.

Campus police investigated Underwood's allegations two years ago, but she "chose not to pursue her police complaint," the university said in a statement.

A campus institutional equity office separately investigated the allegation of an uttered racial comment. "This investigation also did not produce sufficient evidence to confirm the allegations," the statement said.

Photos posted on the Twitter account of the campus newspaper show graffiti on signs and leaded-glass windows urging Trask's firing. Other photos posted by the Duke Chronicle show dozens of students chanting or seated on the lawn outside the administration building.

The university also said Duke's current minimum wage is $12 an hour, compared with the federal and state minimum of $7.50. The school is pushing to require companies with which it contracts for campus services to also pay at least $12 an hour, Duke said in the statement.