By Eliott C. McLaughlin, Michael Pearson and Ben Brumfield
FERGUSON, Missouri (CNN) -- [Breaking news update, 12 p.m. ET]
(CNN) -- A grand jury in St. Louis County will hear evidence Wednesday in the fatal shooting of Michael Brown, county Prosecutor Bob McCulloch told reporters.
[Original story, published 9:33 a.m. ET]
(CNN) -- As U.S. Attorney General Eric Holder prepares to visit Ferguson, Missouri, on Wednesday, a grand jury may also begin hearing evidence in the shooting death of Michael Brown.
Holder's visit comes on the heels of a quieter night that still saw scuffles between police and protesters, some of whom authorities accused of throwing water bottles and urine at them.
Sent by a President troubled by the shooting and the resulting violence, Holder is expected to check in on the federal civil rights investigation into Brown's death August 9. A white police officer shot the unarmed African-American teenager after stopping him as he walked on a Ferguson street.
Police have said Brown tried to shove Officer Darren Wilson back into his car and struggled for his gun. Witnesses who have spoken to CNN and other media say Brown was standing with his hands in the air when he was shot.
Holder's visit and the federal investigation are separate from the St. Louis County grand jury inquiry, which a court spokesman said could begin as early as Wednesday.
Spokesman Ed Magee said Monday that officials were working on getting witnesses lined up to testify Wednesday, but that the schedule wasn't a certainty.
When the grand jury does consider the case, it will do so secretly -- much to the chagrin of those who have called for transparency.
"This community has a distrust for the local enforcement officials. So if you have a secret grand jury proceeding, where nobody knows what the prosecutor presents ... and the grand jury comes back and says we find this (shooting) justified, I think that's going to be very problematic for this community to accept."
St. Louis Alderman Antonio French, who has been a regular fixture at the protests, said people are getting impatient to see how prosecutors plan to handle the case.
"We're on day 12 now," he said. "I think the people expect to see something by now, and they're getting frustrated."
But charges against the officer from either investigation will not come quickly, CNN law enforcement expert Tom Fuentes said.
In the state investigation, forensic details, the autopsy results and toxicology tests are still pending.
And federal investigators will plod ahead slowly, Fuentes said
"If they choose to bring charges against Officer Wilson, they have to go to trial in 90 days."
So, they will take their time to make their case thoroughly, he said.
"They will rather be slow than wrong," he said.
Tuesday night's protests started peacefully.
A few hundred people walked up and down a small area. "Hands up! Don't shoot" was their mantra, as it has been every night.
Many of the demonstrators added a second chant: "We protesters, we don't loot."
Things remained peaceful until late, when a water bottle flew at police.
By that time, most protesters had cleared out. Journalists outnumbered those who remained.
Officers put on helmets and shields, lined up in front of some businesses and demanded a small crowd there clear out.
But when the bottle flew, officers broke into a sprint, chasing after young men.
This prompted a handful of agitated protesters to toss more bottles, glass and plastic.
Missouri State Highway Patrol Capt. Ron Johnson, who's tasked with maintaining peace, told reporters that someone had thrown urine on police.
After the chase, the number of riot police ballooned. Officers brought out dogs. One officer used pepper spray on some in the crowd.
Protesters locked hands in front of a police line, and some urged the crowd to remain peaceful.
Others donned T-shirts printed with the word "peacekeeper," and tried to defuse tensions. Some talked emphatically with young men, who appeared to want to charge at the police.
Johnson credited them for preventing further escalation.
Police arrested 47 people, Johnson said, including a car full of people who he said were armed and had made threats to shoot an officer.
Police and protesters have blamed agitators -- including many from outside Ferguson -- for the violence marring the demonstrations. According to the jail records, some of those arrested Monday night came from New York, California, Texas and Alabama.
Still, many have also criticized the police response.
Gen. Russel Honore, who handled crowd control in the chaos that ensued after Hurricane Katrina in New Orleans in 2005, joined them late Tuesday.
"You're there to protect people," he said. "They need to sense that from you." Looking at crowd members through the scope of a gun sends the wrong message, he said.
Demand for cameras
In a statement Tuesday, Ferguson leaders pleaded for calm and vowed to make changes. Among their promises: recruit more African-Americans to join the overwhelmingly white police force in the largely African-American neighborhood.
They also promised to raise money to outfit officers and police cars with vest and dash cams.
Such cameras could have helped clear up the central question surrounding Brown's death: Was he executed by Wilson while holding his hands in the air, or was he shot after rushing at the officer?
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