Last Updated Nov 11, 2014 4:45 PM EST
WELDON SPRING, Mo. -- Missouri Gov. Jay Nixon vowed that "violence will not be tolerated" as the St. Louis region braces for a grand jury decision on whether to charge a police officer for fatally shooting 18-year-old Michael Brown in the suburb of Ferguson.
Nixon and law enforcement leaders spoke at a news conference at Missouri State Highway Patrol Troop C headquarters in suburban St. Louis.
Nixon said that he was "not convinced" that there would be violence but said that law enforcement in the region have been working "around the clock" to prepare to keep the residents and businesses in the area safe.
A state grand jury is expected to decide this month if Ferguson officer Darren Wilson will be charged in the death of Brown, who was unarmed when he was killed Aug. 9. The shooting led to significant unrest in Ferguson and throughout the St. Louis area, and there is concern protests will escalate after the announcement of the grand jury's decision.
"That ugliness was not representative of Missouri and it cannot be repeated," Nixon said Tuesday.
Nixon added that citizens "must also have the right to express themselves peacefully without being threatened by violent individuals."
"This is America," he said. "People have a right to express their views and grievances but they do not have the right to put their fellow citizens at risks."
During the sometimes violent but often peaceful protests that followed the shooting, police donned riot gear and patrolled in armored vehicles, drawing widespread criticism and raising questions about a program that supplies surplus military equipment to local police departments.
A small number of protesters in those first few days attacked squad cars, tossed Molotov cocktails at officers and, in a few cases, shot guns in the direction of police and looted local businesses. Police responded with tear gas, smoke canisters and rubber bullets. On many nights, dozens of people were arrested.
St. Louis County police initially handled security, but criticism of their tactics prompted Nixon to put Highway Patrol Capt. Ron Johnson in charge. He and other police leaders said the response was necessary to protect officers, protesters and the public.
Every time Johnson walks by the looted shell of the QuikTrip convenience store, he's reminded of the anger that has come to symbolize Ferguson in the wake of Brown's death.
"The destruction here symbolizes this community, and how fragile and crumbled things are here," Johnson told CBS News correspondent Michelle Miller.
Some protest organizers fear police will be heavy-handed after the grand jury announcement.
Ashley Yates of St. Louis, co-creator of the group Millennial Activists United noted that the vast majority of protests have been peaceful and said Nixon should focus on addressing the systemic problems faced by minority communities, "not reactionary policing techniques."
It isn't just law enforcement getting ready for the announcement. Organizers of Yates' group and other protesters gathered Tuesday for training that includes how to take notes and shoot video of police actions on the streets.
"There is a significant effort to make sure that people's rights are protected and that there's no violence on either side," said Andy Stepanian, a spokesman for several protest groups.