The thrust of Saving Sweet Briar’s argument is that the board is violating the will of the school’s founder, Indiana Fletcher Williams, who in 1901 bequeathed her estate, a former plantation, to be operated as an educational institution in memory of her deceased daughter, Daisy.

The legal case has moved quickly. Oral arguments are set for June 4 before the Supreme Court of Virginia.

The Virginia attorney general has initiated mediation talks between the parties. Another round is set for Monday. A Sweet Briar spokeswoman said that officials would participate “in good faith,” but that the school needs “a significant infusion of funds” to survive.

“The college is under siege,” said Sarah Clement, Saving Sweet Briar’s chairwoman, in an interview Saturday morning. “Their decision that they said was bulletproof, was Clorox-clean, dotted every i, crossed every t — it is not bulletproof. There is no done deal, as Jimmy Jones said.”

She was referring to the target of much ire and scrutiny at Sweet Briar, its interim president, James F. Jones Jr. Mr. Jones’s wife is a graduate of Sweet Briar, and their grandniece was among the graduates on Saturday. But Mr. Jones, who has steadfastly insisted the school must close, decided to skip the ceremony.

“In the last 24 hours, it has come to my attention that there are faculty members and alumnae who have threatened, sometimes quite publicly, to repeatedly disrupt the ceremony tomorrow should I preside,” Mr. Jones wrote Friday in an email to students, faculty and staff members and parents of graduating seniors. So, he said, he “reluctantly decided not to participate.”

Even the commencement speaker, Mayor Teresa Tomlinson of Columbus, Ga., a 1987 graduate, is furious about the closing. In an interview on Friday night, Ms. Tomlinson said that two weeks before the board’s announcement, she and her husband pledged to leave $1 million from their estate to Sweet Briar. Now she is busy raising money for Saving Sweet Briar.