BERKELEY, Calif. — Effigies of black lynching victims found hanging at the University of California, Berkeley have sparked debate over whether the images are powerful protest art or just plain tasteless and racist.

The photographic images were found Saturday morning hanging at two prominent spots on campus. They were discovered a few hours before a demonstration against police brutality organized by a black student union was to start. Police are investigating, but officials say they still don’t know who hung the images or the motivation.

The school’s chancellor and provost released a joint statement Saturday calling on those responsible to come forward.

“While we do not know the intent of the effigies, the impact that it has had on our campus community is undeniable,” chancellor Nicholas B. Dirks and provost Claude Steele said in the prepared statement.

Social media sites hosted debates between those who viewed the effigies as art and those offended by the images.

Rodolfo Mendoza-Denton, a UC Berkeley professor of social psychology who studies prejudice and stereotyping, said he sees no redeeming quality in the images hung Saturday.

“Given the volatility of the protests, I think it’s misguided regardless of the protest,” Mendoza-Denton said.

Others, however, said the effigies may have been a form of “guerrilla art.”

Leigh Raiford, an associate professor of African American studies at UC Berkeley, said there is a long history of artists and groups like the NAACP using lynching images as part of a campaign to highlight a history of violent racism in the country.