Katharine Liell, Mr. Booker’s lawyer, said at a news conference this week that the F.B.I. was investigating the case as a possible hate crime.
“We want this investigated as a hate crime, it was clearly racially motivated,” she said, speaking outside the Monroe County courthouse. “We welcome this inquiry and feel we are one step closer to justice,” she added on Facebook.
Mr. Booker and his lawyer could not immediately be reached for comment.
The Indiana Department of Natural Resources, which manages Lake Monroe, is also investigating the incident, James Brindle, a spokesman for the department, said on Wednesday. No arrests have been made, and an incident report was not immediately available.
“Our conservation officers are working with the Monroe County prosecutor’s office,” Mr. Brindle said. Lake Monroe sits on land owned by the Army Corps of Engineers, private owners and the Hoosier National Forest, he said, adding that the state leases land from the corps for recreational purposes.
Mr. Booker spoke at the news conference, addressing a crowd of supporters with signs that read “Black Lives Matter.”
“We’re not a community where you can lynch someone in the street,” he said. “We are a community that is welcoming or inclusive, and we are going to make sure that justice is served.”
In a statement, Mayor John Hamilton of Bloomington and the city clerk, Nicole Bolden, condemned the confrontation, saying that a group “physically assaulted and denounced and threatened with racial epithets one Black resident of Bloomington.”