Wilson's lawyers said their client, who'd become a "poster child for bad race relations"," was behind the scenes the perfect legal weapon. He stayed silent publicly, and when he spoke to investigators and jurors, his version of events was consistent.

They also described a period of life on the run in which Wilson, 28, bounced from house to house but rarely went out in public. There was only one exception. He did get married to Barbara Spradling, a fellow police officer, obtaining a marriage license in Clayton, Missouri.

One lawyer, Neil Bruntrager, said that Wilson used "certain tricks" he'd learned as a police officer to go out incognito, without specifying what they were. He preferred going to movies because of the darkness.In the first weeks after the shooting, Wilson still hoped that he'd be able to reclaim his job as an officer. Though the Ferguson Police Department has not yet officially determined Wilson's future, the decision made little difference, his lawyers said. He won't be returning to that department or any other.

"At first [his thinking] was, 'I want to go back, I'm a cop, I want to still be a cop'," lawyer Danielle Thompson said. "It took some time for him to realise that wasn't exactly going to be what happened." Another lawyer James Towey added: "I think I expressed to him, 'Do you realise your first call [back on the job' will be to a blind alley where you're executed?'"As the grand jury proceedings moved along over the past few months, Wilson's lawyers said they felt confident that they had the upper hand. That's largely because witnesses who did speak publicly told conflicting stories about the 90-second encounter between Wilson and 18-year-old Brown. If the grand jury had determined that Wilson should face a criminal trial, they would have had plenty of ammunition when cross-examining witnesses, they said.

They determined quickly after the shooting that Wilson should not speak publicly - in contrast to George Zimmerman, a volunteer watchman who in 2012 shot black teenager Trayvon Martin in Florida - because it could only hurt his case.

"[Zimmerman] is an idiot, Darren was not," Towey said. "Any criminal defence lawyer that has half a brain says, 'Shut up, don't say a word'."

Wilson gave his first and so far only interview on Tuesday to the ABC network in the US, saying that he didn't think he could have handled the confrontation with Brown any differently. He said he had a clean conscience because "I know I did my job right".

Wilson had been with the Ferguson police force for less than three years before the shooting. He told ABC that Brown's shooting was the first time he had fired his gun on the job.

Asked whether the encounter would have unfolded the same way if Brown had been white, Wilson said yes.

"Everybody says that [his story] was so rehearsed and he was so prepped," Thompson said. "But the way Darren tells the story has not changed from the minute the shooting occurred. He could probably tell it in his sleep if he had to."

"If I could, I'd show you my notes from one hour after it happened," Kloeppel said, referring to an interview Wilson did at Ferguson police headquarters on August 9. "Same story."

Wilson said in his grand jury testimony that he feared for his life during his confrontation with Brown, which he blamed on the big teen, saying the theft suspect reached through his driver's side window, hit him in the face, called him a "pussy" and tried grabbing his gun. Wilson then got off a shot that went through Brown's hand, the only bullet that hit Brown at close range.

Wilson told ABC he felt like it was his duty to chase Brown after the confrontation at his police vehicle. When asked about witness accounts that Brown at one point turned toward Wilson and put his hands up, he responded "that would be incorrect". Brown fell to the ground about 46 metres from Wilson's vehicle, fatally wounded by the last of the seven bullets that struck his body.

The shooting was not necessarily destined to become a flashpoint for so many broader issues. Wilson's lawyers think that the case turned into a perfect storm because of the initial, public testimony of Dorian Johnson, who was walking with Brown when Wilson stopped them.

Johnson said soon after the shooting that the friends weren't causing any harm, and that Wilson - in making the stop - grabbed Brown by the neck while still in the driver's seat of his Chevy Tahoe. Things intensified into a chase, but Brown eventually raised his hands in surrender, Johnson said. Wilson then "fired several more shots"."Total bull," Towey said of the hands-up narrative, adding that Brown's blood trail indicated that he might have been charging toward Wilson as the last shots were fired.

St Louis County prosecutor Robert McCulloch has faced intense criticism for his handling of the grand jury - particularly his decision not to request any kind of charges. Instead, McCulloch left all judgment up to the jurors, deluging them with the kind of evidence you'd normally only see in a jury trial. Questioning of those who appeared in front of the grand jury was fairly friendly.

One Wilson lawyer, Bruntrager, declined to criticise the process, and said there was a reason for running such an informal grand jury - to let witnesses talk freely.Wilson's lawyers said he has no plans to specifically apologise to Brown's family. Following the grand jury decision, Wilson, through his lawyers, released a statement that did not mention Brown. "Even if he gave the most heartfelt apology, they'd still not like it," Towey said.

"Taking a life is a horrible thing to have to do," Bruntrager said. "And yet, the key phrase is, 'to have to do'. Because that is what he thinks. Is that going to make the Browns feel any less grief?"