A Minnesota prosecutor says the police officer who shot and killed a black motorist in suburban St. Paul in July had no good reason to use deadly force.
Reynolds' 4-year-old daughter was also in the vehicle when the shooting occurred.
Other details in the complaint include a report that one of seven bullets fired by Officer Jeronimo Yanez struck the back seat where the young daughter of Castile's girlfriend was sitting. Castile's girlfriend livestreams the aftermath on Facebook and the widely shared video draws protesters to the scene.
Yanez was charged with two felony counts for recklessly firing his weapon.
The fatal shootings of black men and boys by police officers have come under heightened scrutiny since the 2014 death of Michael Brown in Ferguson, Missouri, and led to calls nationwide for officers to be held criminally responsible.
John Choi, the Ramsey County attorney, said at a news conference in St. Paul, on Wednesday morning that Jeronimo Yanez, the officer who shot Castile, would also be charged with endangering the lives of Reynolds and her 4-year-old daughter, who was also in the auto.
"No reasonable officer, knowing, seeing and hearing what officer Yanez did at the time, would've used deadly force under these circumstances", Choi said.
Choi says Castile had informed Yanez when the officer approached the auto that he had a handgun.
"My conscience tells me that it would be wrong for me to ask a grand jury to make this decision when I know what needs to be done", Choi said.
July 14: A funeral for Castile at the St. Paul Cathedral draws thousands of mourners.
One of the officers told state investigators that Clark's hand reached his gun during a struggle.
Yanez was also charged with two counts of "dangerous discharge of a firearm", which endangered Castile's girlfriend, Diamond Reynolds, and her 4-year-old daughter, who were also in the vehicle.
Wednesday, Ramsey County Attorney John Choi's office charged St. Anthony police officer Jeronimo Yanez with second-degree manslaughter and multiple counts of unsafe discharge of a firearm.
Yanez shot and killed 32-year-old Philando Castile on July 6 during a traffic stop.
News of Castile's July 6 death spread like wildfire on social media when his fiancée, Diamond Reynolds, live-streamed the aftermath of the shooting on Facebook. Then Castile calmly said that he had a firearm and a permit to carry it, Choi said.
Choi said Castile's gun was later found deep in a front pocket of his shorts, with a loaded magazine but no bullet in the chamber.
Castile, 32, told the officer he was legally carrying a gun and and paramedics found a loaded pistol in his shorts, but "the mere presence of a firearm alone can not justify use of deadly force", Choi said.
A Minnesota police officer has been charged with second-degree manslaughter in the killing of a black man in a St. Paul suburb.
August 24: The St. Anthony Police Department says it put Yanez back on administrative leave after he had briefly returned to limited duty, citing "concerns and other feedback from the community".
Michael Slager, a white officer in North Charleston, South Carolina, who has since been fired, is now on trial for murder in the 2015 death of 50-year-old Walter Scott, an unarmed black man who was shot while running from a traffic stop.
Yanez is Latino. Castile was black.
But family members have claimed that Mr Castile, an elementary school cafeteria worker, was racially profiled.
Choi said Yanez fired seven rounds into the auto.
Authorities are planning to provide an update about their investigation into the killing of a black man who was shot by a Minnesota police officer.