Donald Thurman, 26, is charged with first-degree murder and sexual assault in the slaying of 19-year-old Ruth George early Saturday. Thurman allegedly confessed after being arrested Sunday morning, police said.
Prosecutors claim Thurman became upset when George ignored his catcalls.
Lightfoot is calling George's death "alarming and devastating."
"As a woman, I am shaken to my core by such cowardly violence," the mayor said.
Lightfoot addressed "perpetrators of this type of harassment," saying that, "Women do not owe you anything. Ever."
A judge has ordered Thurman be held without bail. Police said he has no connection to the university and didn't know George.
The 19-year-old sophomore was found strangled in the backseat of her family's car at a UIC parking garage near Halsted and Taylor streets.