A suspect is in custody for a deadly shooting at an MLK Day celebration. Officers arrested 18-year-old Ol Wallace on Tuesday at an apartment complex on Salado Creek Drive. Investigators say 61-year-old Johnnie Mobley Jr. was killed when Wallace opened fire on a crowd of dozens of people who had gathered on Spriggsdale Boulevard near I-10. Two men and two women were wounded. Wallace is charged with one count of murder and four counts of aggravated assault with a deadly weapon. Police don't yet have a motive.