The shooting on July 6 previous year, in the Minneapolis suburb of Falcon Heights, gained widespread attention because Mr Castile's girlfriend, Diamond Reynolds, live-streamed its gruesome aftermath on Facebook.
Castile was then heard telling him calmly: 'Sir, I have to tell you, I do have a firearm on me'. In the video, Yanez pulls Castile over to tell him his brake light is broken and asks for his driver's license.
The 29-year-old police officer was found not guilty on charges of second-degree manslaughter and two felony counts of intentional discharge of a unsafe weapon for endangering the safety of Mr Castile's girlfriend, Diamond Reynolds, and her four-year-old daughter, who were both in the auto at the time. Prosecutors portrayed Yanez as a nervous officer who lost control of his traffic stop.
Yanez then immediately grabs his gun, aims inside the auto and rapidly fires seven bullets into the driver's side while Reynolds is screaming in the background.
Reynolds maintains that Castile was reaching for his identification in his wallet after, as the video shows, he tells Yanez that he has a firearm. And yet, last week Yanez was found not guilty on all counts.
The video then shows Reynolds' young daughter exiting the back passenger door by herself, while Yanez's partner picks her up and ushers her away.
Before Castile could finish his sentence, Yanez drew his own gun. Minnesota police officer Jeronimo Yanez is free.
"Don't reach for it then", Yanez says. At the trial, Yanez said he "was able to see the firearm in Mr. Castile's hand". After warning Castile multiple times not to pull out his gun, Yanez shot Castile. Yanez can be heard yelling that before he fired seven shots into the vehicle.
The city says it concluded the public "will be best served" if Yanez no longer works for the city. "He didn't tell me where the [expletive deleted] gun was". He added, "I don't know where the gun was". It's hard to watch Yanez kill Castile and not empathize with his mother.
The jurors in the Yanez trial deliberated for five days, and at one point were deadlocked, before finally deciding that the Minnesota police officer was not guilty. Yanez, who testified he thought he was going to die, was acquitted of manslaughter.
The St. Anthony Police Department later announced he would not return to the force.