community members at one church diamonding al ra -- alvarez step down. >> i want to pray for the calm of the city. because we can be -- we could be on the verge of another ferguson. >> reporter: but alvarez defends the lengthy investigation, saying the time was needed to review evidence and charge van dyke with first degree murder. >> it's the first time it's happened in over 30 years in chicago. so, these are very heavy charges. >> reporter: van dyke's defense argues he fired at mcdonald because he feared for his life. the teen was carrying a three-inch knife. but investigators say he was not threatening van dyke at the time of the shooting. the citizen watchdog group invisible institute says at least 20 complaints were filed against van dyke in his 14-year career as an officer, including allegations of using excessive force and racial slurs. but so far, van dyke was not disciplined. abc news confirmed 18 complaints. and all eyes now will be right here on chicago's magnificent mile. protesters who say they want their demonstrations to have an economic impact plan to protest as black