Michael Brown, an unarmed black teenager, was fatally shot on Aug 9, 2014, by white police officer Darren Wilson in Ferguson, a suburb of St. Louis, Missoiuri. The shooting led to weeks of protests.

On Nov 24, the grand jury - made up of nine whites and three blacks - found that Wilson, 28, had killed the 18-year-old in self-defence. The decision not to indict Wilson sparked rioting, looting and arson attacks in Ferguson overnight.

Here's what you should know about the case:

A demonstrator carries a picture of Michael Brown during a protest along Florissant Avenue on Aug 16, 2014 in Ferguson, Missouri. -- PHOTO: AFP

What happened?

Just before noon on Aug 9, Brown, 18, and Dorian Johnson left Ferguson Market and Liquors, a convenience store. Surveillance video showed Brown stealing some cigars. They headed toward their homes, walking in the middle of a street which was usually quiet at that time of the day.

At 12.01 pm, officer Darren Wilson arrived at the street, driving alone in his police car. Speaking through his window, he told Brown and Johnson to move away from the street.

A scuffle broke out between Wilson and Brown. Forensic evidence revealed that the officer's guns were fired twice in the car, first striking the teenager in the arm and missing him the second time.

Brown then ran away and the officer got out of his car and pursued Brown, continuing to fire. Autopsies show that Brown had been shot at least six times.

Which parts of the shooting are in dispute?

Accounts differ on who started the altercation and whether there was a struggle for the officer's gun. Wilson said that he was pinned in his vehicle and feared for his life while struggling over his gun with Brown. He said that the teenager punched and scratched him repeatedly, leaving swelling on his face and cuts on his neck.

But Brown's friend Johnson said Brown never reached for the gun and it was the officer who tried to choke Brown, grabbed his arm to pull him into the car and threatened to shoot.

The police officer also claimed the victim had been running toward him when he fired the fatal shots. Some witnesses said that Brown appeared to be surrendering with his hands in the air when he was killed.

Brown family attorney Daryl Parks points on an autopsy diagram to the head wound that was likely fatal to Michael Brown during a news conference in Ferguson, Missouri on Aug 18, 2014. -- PHOTO: REUTERS

What did the autopsies show?

A private autopsy requested by Brown's family showed that he was shot at least six times: four times in the right arm and twice in the head. The autopsy was performed by Dr Michael M. Baden, the former chief medical examiner for the City of New York.

Dr Baden said that one of the bullets entered the top of Brown's skull, suggesting that his head was bent forward when it hit him, and caused a fatal wound.

No gunshot residue was found on his body, which would suggest that the rounds were not fired from very close range.

Dr Baden, however, did not have access to the teenager's clothing, which could contain residue.

Local officials have not released their report on the initial autopsy, though a person briefed on the report said that it showed evidence of marijuana in Brown's system.

A third autopsy conducted by a military doctor as part of an investigation by the Justice Department also found that the teenager was shot six times.

Demonstrators hold up roses while protesting the shooting death of Michael Brown make their voices heard on Aug 18, 2014 in Ferguson, Missouri. -- PHOTO: AFP

How long did the protests last?

The shooting prompted weeks of demonstrations and a response from the police that included tear gas and rubber bullets. Confrontations between protesters and law enforcement officers continued even after Governor Jay Nixon deployed the Missouri National Guard to help quell the unrest. Since then, protests in Ferguson have persisted in smaller numbers.

In early October, the Ferguson Police Department handed over responsibility for policing protests to the county police department, which is larger and better equipped.

Police launch tear gas at demonstrators protesting the killing of teenager Michael Brown on Aug 17, 2014 in Ferguson, Missouri.-- PHOTO: AFP

What are the problems in Ferguson?

Ferguson, a town of 21,000 residents in St Louis, Missoiuri, has wrestled with racial tension for decades. While most of St. Louis County is white, Ferguson and neighbouring towns are predominantly black. The city's leadership and police force have remained mostly white.

Ferguson's mayor and five of its six City Council members are white. Only three of the town's 53 police officers are black.

There is frustration among blacks who say local authorities are not attuned to their concerns.

Aliyah Woods, 45, once petitioned Ferguson officials for a sign that would warn drivers that a deaf family lived on a block. But the sign never came. "You get tired," she said. "You keep asking, you keep asking. Nothing gets done."

There have been a series of reported incidents that have added to the unhappiness among the African Americans. For example, community members voiced anger earlier this year after the all-white, seven-member school board for the Ferguson-Florissant district pushed aside its black superintendent for unknown reasons. That spurred several blacks to run for three board positions up for election, but only one won a seat.

In another incident, a white police lieutenant was sacked after it emerged that he had ordered officers to target blacks in shopping areas.

Experts say the protests and violence in Ferguson is emblematic of growing suburban poverty, particularly since the last recession in 2008. The poverty rate was 22 per cent in 2012, the most recent available, up from 10.2 per cent in 2000, according to US Census Bureau figures.

While Ferguson's median income in 2000 was on par with that of Missouri that year, it has since fallen behind. The median income of US$37,000 (S$46,032) trailed the statewide figure of US$47,300 in 2012.

Source: New York Times, Washington Post, Bloomberg, AFP, Reuters

* This article was first published on Aug 19, 2014, and updated on Nov 26, 2014.