The F.B.I. is helping American University in Washington, D.C., investigate an episode in which bananas were found hanging from nooses on campus this week, a spokeswoman for the agency said on Wednesday.

The bananas were found at the university on Monday, the same day a black woman took office as the student government president for the first time in the institution’s history.

The bananas had short messages scrawled on them, including “AKA FREE,” an apparent reference to Alpha Kappa Alpha, a predominantly black sorority of which Taylor Dumpson, the new student body president, is a member; and “HARAMBE BAIT,” referencing the gorilla at the Cincinnati Zoo who was killed last May after a child fell into its enclosure.