There is no indication yet as to whether or not officer Darren Wilson will face charges for the death of Michael Brown on August 9, 2014 in the community of Ferguson, just outside St Louis.
He could be indicted for first or second degree murder, or manslaughter — or the grand jury could decide that he acted in self-defense and that there is no need for him to go on trial.
Brown, an 18-year-old high school graduate planning to go to technical college, was shot at least six times by Wilson.
The grand jury announcement will be made at the Buzz Westfall Justice Center in Clayton, Missouri, at 8:00 pm (0200 GMT Tuesday), St Louis County prosecutors said.
Brown’s shooting sparked weeks of sometimes violent protests and a nationwide debate about police tactics and race relations.
The teenager’s family called for non-violence and a four-and-a-half-minute silence after the announcement is made. Church leaders have also called for calm.
The time reflects the approximately four hours their son’s body reportedly lay in the road after he was shot.
– Plea for non-violence –
“We are not here to be violent. We are here in memory of our son. We are here for protection of all children,” Brown’s relatives said.
“We lift our voices to ensure black and brown men, women and children can live in this country without being devalued because of the color of our skin.”
Ferguson’s mainly African American community of 21,000 has been on edge for days, braced for further protests should the officer not be indicted.
The mostly black suburb has an overwhelmingly white police force and residents complain of years of racial prejudice and heavy handed police tactics.
Missouri’s governor declared a state of emergency and called up the national guard last week in readiness. The FBI has also deployed extra personnel.
“There’s going to be a war. Starting from today. A war,” shouted an angry neighbor wearing an “I am Michael Brown” T-shirt at the spot where Brown died.
“By activating the National Guard, you’ve basically told black people that’s a war on us,” said the man, who identified himself only as D, convinced the jury would exonerate Wilson.
It emerged Monday that Wilson, who has barely been seen in public since the shooting, married a fellow Ferguson police officer last month after obtaining a marriage license in St Louis.
Shops are boarded up in Ferguson and schools in the Ferguson-Florissant District announced they would be closed Tuesday for the safety of staff and pupils.
Barricades have been erected around the Buzz Westfall Justice Center in Clayton, where the grand jury has been meeting.
– Gun sales up –
Paul Bastean, owner of the Ultimate Defense Firing Range and Training Center, around 20 miles (32 kilometers) west of Ferguson in St Peters, said business had grown exponentially as a result of anxiety about the jury announcement.
Typical sales of five to seven guns a day have risen to 20-30 in the last week, while courses for November and December are fast selling out.
His shooting range usually attracts 70-100 people each Saturday but 261 came last Saturday, said Bastean, who is also an active duty police officer.
The majority of their customers are white and around 40 percent are women, he said. Many are anxious about threats made on social media.
But the vast majority of protests have been peaceful.
More than 100 demonstrators marched through St Louis late Sunday.
“This is what democracy looks like,” chanted the crowd, banging drums and waving placards saying “Black Lives Matter.”
“The whole damn system is guilty as hell,” they shouted.
Police, who were criticized for a heavy-handed response to the demonstrations in August, kept a discreet distance and the demonstrators dispersed peacefully.
“It’s a good showing,” said teacher Angela Kelly, who marched alongside her son.
“This is about more than Michael Brown. It’s about police brutality, it’s about racism that is still everywhere in our society.”
Wilson reportedly told the jury he acted in self-defense after tussling with Brown. Others say Brown had his hands in the air when he was shot dead- AFP