When the fatal confrontation occurred a short time later, after the high-speed chase, Mr. Stockley said, Mr. Smith was reaching for something as the officers stood at his driverâs side window, and he assumed it was a gun.
The defense rejected suggestions that the officer had planted anything. After the shooting, Mr. Stockley went back to the police vehicle to get a medical dressing that slows bleeding, they said, not to get an extra gun. An expert testified that someone can hold a gun and not leave DNA on it, so the absence of Mr. Smithâs DNA on the gun was not proof that he had not held it.
In the end, Judge Timothy Wilson of the St. Louis Circuit acquitted Mr. Smith on Friday morning, saying he was âsimply not firmly convinced of defendantâs guilt.â
What happened in St. Louis when the verdict was announced?
Protesters gathered within minutes, and they have marched each day since then, in downtown streets, entertainment districts and a suburban mall. The marchers have included people of a wide range of ages and of different races, and their numbers and makeup have shifted significantly at various points during the weekend.
Most demonstrators have been peaceful, but there were violent incidents after dark both Friday and Saturday. At least 11 law enforcement officers were injured, the mayorâs house was vandalized and windows were broken at several businesses and a public library. The police said they made at least 42 arrests on a variety of charges, including rioting and assault.
The rock band U2 and the singer Ed Sheeran canceled concerts that were scheduled for downtown St. Louis, citing security concerns, and many school districts in the region canceled weekend activities.
Another largely peaceful protest took place on Sunday afternoon but it escalated in the evening when a smaller group of roughly 100 demonstrators marched from the cityâs police headquarters through the heart of the downtown. They knocked over large concrete flower pots, trash cans and newspaper stands on several blocks, and threw rocks through several windows at the Marriott St. Louis Grand Hotel.
Police officers on bicycles and in cars swarmed the area, and at least nine people were arrested.
What makes St. Louis different?
Elected leaders, protesters and other residents of this region are deeply aware of the areaâs early role in the current national debate over how police officers treat black people. The region became the focal point of that debate in 2014 following the death of Michael Brown, an unarmed black man who was shot by police in Ferguson, one of the many small municipalities that surround St. Louis.
How have politicians responded?
The regionâs top elected offices â governor of Missouri and mayor of St. Louis â have both changed hands since the events in Ferguson.
Gov. Eric Greitens, a Republican who took office this year, has repeatedly criticized his Democratic predecessorâs approach to the protests that followed the Ferguson shooting, saying that while peaceful marchers should be respected, if âyou break a window, youâre going to be behind bars.â
Anticipating the possibility of trouble, he placed the Missouri National Guard on standby on Friday before the verdict was announced. âIn the past, our leaders let people break windows, loot, start fires,â Mr. Greitens wrote Sunday morning on Facebook. âThey let them do it. Not this time.â
The mayor of St. Louis, Lyda Krewson, a Democrat, has taken a less confrontational approach, even though her own house was vandalized during the demonstrations on Friday.
She seemed to try to convey a sense of normalcy in the city, while also promising to address protestersâ concerns. Before the protests on Saturday night, she said that âI think itâs quite safe right now,â and that the weekendâs events showed the need for âcoming together to have a better St. Louis for all of us.â
Ms. Krewson, who is white, leads a city with nearly equal numbers of black and white residents and a long history of racial division. She outpolled several well-known African-American candidates in the mayoral election in the spring.