(CNN) -- Authorities are investigating whether Michael Brown's stepfather intended to incite a riot last week when he urged a crowd in Ferguson, Missouri, to "Burn this bitch down" after the grand jury's decision was announced, the city's police chief said Tuesday. No charges have been filed against Louis Head in the incident, but police have interviewed people who know Head and who were with him November 24, the day a prosecutor announced that Officer Darren Wilson (who has since resigned) would not be indicted in the August 9 shooting of Michael Brown, Police Chief Tom Jackson said. Shortly after St. Louis County prosecuting attorney Robert McCulloch's announcement, Head stood above a crowd of demonstrators -- some of them shouting "F--- the police!" -- and yelled, "Burn this motherf---er down!" and "Burn this bitch down!"