A group of conservative UC Berkeley students told the U.S. Department of Justice this week that they canceled last week’s controversial Free Speech Week event on campus for fear they would be “subjected to a criminal police investigation” by the university.

The students are asking the Justice Department to investigate what they say is retaliation by the university.

A lawyer for the Berkeley Patriot — the student group that invited far-right showman Milo Yiannopoulos and other right-wing speakers to campus before canceling at the last minute — told the Justice Department Tuesday that the students were the targets of a police investigation that UC Berkeley Chancellor Carol Christ announced on Sept. 21 specifically to retaliate against them for filing a prior federal complaint.

Campus spokesman Dan Mogulof called the allegations “utterly unfounded” and said the complaint “seems like a desperate attempt to avoid any responsibility for the collapse of the events.”

The investigation by campus police looked at whether a hate crime occurred when someone hung posters from an anti-Muslim organization featuring images and names of individual faculty and students and calling them terrorist supporters, Christ told The Chronicle at the time. She said the police would also look at whether chalk messages on campus constituted a hate crime. The messages used a slur for gay people, called for a border wall against immigrants and to “deport them all,” and said that abortion is genocide.

Christ said the incidents were “very disturbing to me” and that many UC Berkeley students were brought to this country illegally as children. The chalkings are “horrible,” she said, and she characterized the posters as “hate acts across campus.”

In the federal complaint, the students’ attorney, Marguerite Melo, characterized them instead as “topics of interest of a conservative-political nature.”

The complaint accuses Christ of blaming students for distributing the posters and for creating the chalk messages, and claims that Christ implied as much in an all-campus email and in remarks to The Chronicle.

“Some of those students were affiliated or supporters of the Berkeley Patriot,” Melo told the Justice Department in the complaint.

The disclosure was the first indication that students had any role in the chalking or in distributing the posters.

Melo said she interpreted Christ’s message as saying that “conservative students will be subjected to a criminal police investigation (and implicitly a possible prosecution) for exercising their First Amendment rights.”

Because of that, she said, the Berkeley Patriot group canceled Free Speech Week.

The new complaint does not mention that the lineup of announced speakers voluntarily dropped out or said they had never been invited in the first place. Nor does it say that the student group’s leaders had told The Chronicle that they canceled the event because they felt threatened about hosting the right-wing event on the left-leaning campus. In February, a riot caused the last-minute cancellation of another talk by Yiannopoulos on campus.

The students from the Berkeley Patriot referred all questions to Melo, who said police had not questioned them.

Sgt. Sabrina Reich of the UC police said the investigation is finished, and that no hate crime occurred. She said that after learning about the chalking on Sept. 18, officers spoke with students on Sproul Plaza, where the messages appeared.

“Upon investigation, the content of the chalking was determined to be political slogans, and there was no hate speech involved,” Reich said. The posters included offensive speech, she said, but the contents “did not qualify as a hate-related incident” because it didn’t refer to any of the protected characteristics in the state penal code.

In their complaint, the students told the Justice Department that the investigation was meant to get back at them for filing an earlier complaint, on Sept. 19, that claimed the campus “has become downright physically dangerous this past year for conservative students.” It asked the federal agency’s Office of Civil Rights to investigate whether UC Berkeley has failed to protect the First Amendment rights of those students.

No one from the Justice Department has approached UC Berkeley, Mogulof said, noting that the campus had spent $800,000 on security for the event, though the students withdrew as sponsors.

“We aren’t in the habit of spending nearly $1 million on events we are trying to cancel,” he said.

Nanette Asimov is a San Francisco Chronicle staff writer. Email: nasimov@sfchronicle.com Twitter: @NanetteAsimov