It took just three minutes.
In a speck of time on a snoozy side street, two lives intersected when a white police officer named Darren Wilson and a black teenager named Michael Brown - one in a patrol car, the other on foot - found themselves together on Canfield Drive.
When they met at 12.01pm on August 9 on this street in Ferguson, Missouri, the two were coming from different places, different mindsets - Brown filling free hours with a friend, Wilson coming off an emergency call about a baby struggling to breathe.
Brown, barely 18, stood 1.93 metres and weighed 132kg. He wore a St Louis Cardinals baseball cap. Wilson, a lanky 28-year-old with short-cropped blond hair who had six months earlier won a commendation for "extraordinary effort in the line of duty", steered a police cruiser behind him.
At 12.04, Brown was dead, shot multiple times by Wilson. "Big Mike," as his friends called him, did not have a gun.
The conflicting accounts of those three minutes - the tortured exercise of assigning blame - have provoked intense protests and turned this inner-ring St Louis suburb into a parable of race, class and justice.
There has been no resolution, no definitive account of what happened in that flash of a hot afternoon or of the two men at the centre of it.
Police records, public documents and more than a dozen interviews are beginning to reveal details of the killing and clarify points on a timeline that began with a theft of less than US$50 worth of cigars from a convenience store and culminated with Brown's death.
A key witness - Brown's friend Dorian Johnson - has told the FBI that he thought the robbery was a "prank", said Johnson's attorney. In an interview with federal agents, Johnson has said Brown was hit by one bullet, then - as Brown pleaded for his life - Wilson fired "five or six" more times.
And when the shooting stopped, Johnson and his legal team have told investigators, the police officer who pulled the trigger did nothing to save the man he'd just shot. "The officer doesn't attempt to resuscitate," said Johnson's attorney, former St Louis mayor Freeman Bosley Jr. "He does not call for medical help. The officer didn't call it in that someone had been shot."
Both men are now forever entwined with Ferguson, but neither had deep roots here. Brown was only spending the summer with his grandmother while making plans to attend a vocational school. Wilson was in his fourth year on the police force after working for two years on a force nearby. He lives some distance away in the suburb of Crestwood.
The fraught relationship between African Americans, a majority in Ferguson, and the nearly all-white police force long preceded the eruption of protests. In interview after interview, black men and women talked about their fears of random stops while driving in the city, as well as in neighbouring municipalities.
"More than four people in the car, they're going to pull you over," said Earl Lee Jr, a 41-year-old warehouse worker who lives in a nearby suburb. "Tint on your windows, they're going to pull you over. Too early in the morning, they think you're up to something. Too late, they think you're up to something. When are you supposed to drive?"
Law-enforcement officials have given fragmented accounts that differ from Johnson's recollection. In their telling, Brown was the aggressor.
Jon Belmar, the St Louis County chief of police, has said that Brown reached for Wilson's gun and that a shot was fired inside the vehicle.
Ferguson Police Chief Thomas Jackson said Wilson ended up with "a swollen face". But Jackson has given a series of conflicting accounts of the event.
In a news conference on Thursday, he released video surveillance from the convenience store, leading many to think he was implying a connection between the robbery and the shooting. Later that day, Jackson reversed himself, saying there wasn't a connection between the robbery and Wilson's confrontation with Brown. Hours later there was a revision: Jackson said Wilson saw cigars in Brown's hand and "realised he might be the robber".
At the Canfield Green apartment complex, steps away from a memorial that has swelled in the street where Brown died, a sign reads: "Caution - killer cop on the loose."
Ongoing local and federal investigations - and perhaps, eventually, a judge or jury - may help reconcile the opposing images of those involved and the saga of what happened here. The robbery, the shooting, the three-minute collision of two lives.