Officer Norvelle Brown, a 22-year-old Black man and one-year member of the St. Louis Police Department, was ambushed and shot on the evening of August 15, 2007, in an alley in the 1600 block of Semple Avenue. Despite being able to radio for help, he was critically wounded; an undercover officer rendered CPR and took him to a hospital, but he died. The fatal bullet entered through the arm opening of his bullet-resistant vest.

Two people were arrested two days later, on August 17, 2007: a 15-year-old who reportedly had expressed an intent to kill a police officer, and an 18-year-old accomplice. The 15-year-old was certified to stand trial as an adult, convicted of first-degree murder and armed criminal action, and sentenced on October 9, 2009, to life without parole.