Ferguson decision may come Friday

• St. Louis police chief says his officers are ready for all scenarios


• Grand jury weighs evidence to determine whether Officer Darren Wilson will face charges


• Wilson fatally shot Michael Brown in August, setting off protests

Ferguson, Missouri (CNN) -- A tense Ferguson is awaiting to hear whether a St. Louis County grand jury believes Officer Darren Wilson should stand trial in the fatal shooting of unarmed teen Michael Brown.

The grand jury hearing evidence plans to meet Friday for what might be its final session.

A decision on whether to charge Wilson could come the same day, law enforcement officials briefed on the plans said.

Jurors have until January, but the prosecutor's office has said a decision could come this month.

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For weeks, lawyers, analysts and journalists have speculated on when it will be announced.

Ferguson became a flashpoint for racial tension after the teen's shooting; Brown, 18, was black, the officer is white.

Street demonstrations and violence erupted, and heavily armed police came face to face with angry protesters demanding justice.

Some predict that will be the case again when the grand jury's decision is announced.

Along West Florissant Avenue, the ground zero of violent protests, businesses put back the plywood boards they had taken down from their windows and doors.

What happens next?

If a decision comes Friday, prosecutors are expected to provide law enforcement with 48 hours notice before making a public announcement, possibly on Sunday.

The current plans could still change and prosecutors could shift the planned grand jury session, the law enforcement officials said.

Prosecutor Robert McCulloch has said he plans to make public all evidence and testimony presented to the grand jury, but there is growing concern on how to deal with identities of people who have testified, the sources say.

There are concerns some witnesses could be put at risk once their testimony and identities become public, law enforcement officials said.

In some cases, witnesses might have testified differently under oath, providing different accounts than the ones they gave in media interviews, the official explained. Others may have provided testimony that may be interpreted as helpful to the officer's account of the August 9 shooting.

The prosecutor's office said it hasn't decided whether to redact names of witnesses.

'Three months to prepare'

St. Louis Police Chief Sam Dotson has said his officers are ready for whatever happens.

"We've had three months to prepare. ... Acts of violence will not be tolerated," he said. "Our intelligence is good. Our tactics are good. We can protect lawful people and at the same time arrest criminals."

St. Louis Mayor Francis Slay wrote the city's aldermen to explain that 400 National Guard troops would be requested for the city.

They will be placed with police officers at 45 locations around the city to prevent violence and property destruction.

The city's police will wear normal uniforms, as "we do not want to appear to militarize our response to the demonstrations and want to do everything we can to de-escalate," the mayor wrote, adding that police may don riot gear if public safety demands it.

"If our officers put on their personal protective gear, it is not to intimidate peaceful protesters. It is for the sole purpose of keeping everyone safe," he wrote.

Area school superintendents wrote a letter to city officials and authorities requesting that they announce the grand jury's decision on an evening or weeknight so it doesn't affect about 20,000 students traveling back and forth to schools.

Many parents received notice to fetch their children from school if the decision comes out earlier in the day.

A group of community member has asked for 48 hours' notice before the ruling is made public. It also released 19 "Rules of Engagement" that touch on major points of contention between protesters and police.

The group wants assurances that neither police nor the government will interfere with the flow of information, as well as a guarantee that police won't use rubber bullets, armored vehicles, rifles or tear gas. The group also requested that officers wear attire "minimally required for their safety" and that "specialized riot gear be avoided except as a last resort."

Nationwide response

Brown's shooting on August 9 also touched a national nerve, with protests decrying racism and police brutality taking place around the country since his death.

The Ferguson National Response Network expects that reaction to the grand jury ruling will not be limited to the St. Louis area. It has set up a Tumblr account advertising about 90 "planned responses" to the ruling. They will take place from West Palm Beach, Florida, to New York, Chicago and Los Angeles.

Brown's supporters have turned out in force, but Wilson's supporters have demonstrated on occasion as well.

CNN's Jake Tapper contributed to this report.