CLAYTON, Mo. - A small group of protesters has gathered outside a suburban St. Louis building where a grand jury is expected to convene to consider possible charges against the Ferguson police officer who fatally shot 18-year-old Michael Brown.

The roughly two dozen protesters chanted, prayed and held signs outside the St. Louis County Justice Center in Clayton, Missouri, on Wednesday. They called for county prosecutor Bob McCulloch to relinquish control of the case to a special prosecutor, among other things.

About 20 police officers stood outside the building's front entrance, which was also blocked off by yellow police tape.

It could be weeks before the grand jury decides whether Officer Darren Wilson should stand trial for Brown's Aug. 9 death.