Updated

Effigies of black lynching victims found hanging on a Northern California college campus 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 the campus of the University of California, Berkeley. 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 hanged the images or the motivation.

"It's unclear if this is racially motivated effort or an effort at something else," campus spokeswoman Claire Holmes said.

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

Berkeley Pastor Michael McBride told the Oakland Tribune that he sees no redeeming quality to the display.

"This is racial terror they are experiencing," said McBride, who is also co-director of Intervarsity's Black Campus Ministries at UC Berkeley. "I don't care if it was a white person, a black person, a blue person, if it was an adversary or ally, these images strewed across campus have terrorized my students."

Others, however, said the effigies may have been a form of "guerrilla art" and that images of lynching victims have been used by artists in the past.  The rap group Public Enemy used a photograph of two lynching victims on the cover the single "Hazy Shade of Criminal" released in 1992.

Leigh Raiford, an associate professor of African American studies at UC Berkeley, told the San Francisco Chronicle that the effigies may have been created to provoke thoughtful discussion about historical black repression.

"To me this suggested a really powerful public art installation that was trying to provoke people to make a historical connection between the history of lynching, state violence against black folks and the contemporary situation that we're faced with around police brutality and these non-indictments,"

A black student union representative said the group is also mystified about who hanged the effigies and why.

"We hope that it's someone who wanted to bring attention to the issue," said Spencer Pritchard, 21, a Berkeley student who helped organize the Berkeley demonstration.

About 300 people participated in the peaceful Berkeley protest Saturday afternoon. Many of them later joined a larger demonstration in Oakland that was mostly peaceful, though police arrested 45 people.