The number of police officers charged with murder or manslaughter in on-duty shootings in the U.S. more than tripled in 2015, according to data compiled by a criminologist who researches police crimes, corruption and misconduct.
In 2015, 18 officers were charged in fatal on-duty shootings, said Philip Stinson, who teaches at Bowling Green State University in Ohio. From 2005-14, only 47 officers were charged, for an average of fewer than five per year.
Stinson attributes the spike in part to the rise in video evidence from body cameras, dashboard cameras, surveillance videos and smartphones.
Video evidence played a big role in many high-profile cases that resulted in charges, like that of Walter Scott in South Carolina, who was killed after a traffic stop. A video of the shooting showed North Charleston police officer Michael Slager firing several times at Scott's back while he was running away.
Slager has been charged with murder and is awaiting trial.
Overall, charges remain a rarity in fatal shootings by police. Officers are legally justified in using deadly force if they have a reasonable fear for their lives or the lives of others.
Stinson said juries appear reluctant to second-guess officers who use deadly force in quickly escalating situations, and that prosecutors are also hesitant to bring charges in a case they may not be able to win.
In 2015, a Washington Post study found that police fatally shot nearly 1,000 people across the nation that year.
In Minnesota, at least 12 people were shot and killed by law enforcement in 2015. None of the officers involved have been charged.
Nov. 24, 2015: Michael Kirvelay
The case will head to a grand jury in May for consideration of criminal charges.
Minnesota Bureau of Criminal Apprehension officials say Columbia Heights Sgt. Erik Johnston and Fridley Officer Shawn Murphy were responding to a report of a person with a gun at a Columbia Heights business. The Department of Public Safety said the officers shot Kirvelay after he refused to show his hands.
Later, Kirvelay's family said they first thought he'd been carrying a BB gun, but now they're not sure he even had that.
Bill Kirvelay said his brother was paranoid and acting in an erratic way.
Nov. 15, 2015: Jamar Clark
On Wednesday, Hennepin County Attorney Mike Freeman announced officers Mark Ringgenberg and Dustin Schwarze will not be charged. Freeman said evidence showed Clark was not handcuffed and had reached for an officer's weapon during a struggle.
Clark, 24, was shot by police during a confrontation in north Minneapolis after officers reportedly tried to stop him from interfering with a paramedic crew treating his girlfriend outside a late-night birthday party.
• Full coverage: The Jamar Clark case
Conflicting accounts over whether Clark was handcuffed when he was shot sparked community protests and widened racial tensions between police and African-Americans.
Nov. 1, 2015: Luverne Christensen
In February, the McLeod County Attorney's Office announced that no charges would be filed against McLeod County deputy Matthew Wyatt.
The Hutchinson Police Department said officers from several agencies were responding to a report of a verbal disturbance at a residence in Hutchinson when a struggle ensued between Christensen and officers.
The BCA said Christensen produced a handgun and fired once, hitting Hutchinson officer Jacob Willers in the leg. Wyatt returned fire, striking Christensen.
Sept. 30, 2015: Robert Christen
In February, the Kanabec County attorney announced no charges would be filed against Kanabec County deputy Shanna McIalwain.
The BCA said McIalwain responded to a 911 call from a man threatening to kill someone. After McIalwain arrived, Christen attacked her, punching her in the head.
Kanabec Sheriff Brian Smith said McIalwain did not fire her weapon right away.
"He continued to quickly advance on her, almost bull-rushed her," Smith said, "and ended up knocking her gun aside and began to beat her about her head and she felt she was gonna lose consciousness and going down and shot him, multiple times."
Sept. 24, 2015: Philip Quinn
In February, a grand jury concluded officers Joe LaBathe and Rich McGuire were justified in using deadly force in the fatal shooting of Quinn, 30.
Police said the St. Paul man was shot after running with a screwdriver toward an officer in a "very aggressive manner."
Family members had described Quinn as mentally ill.
Aug. 22, 2015: Adam Schneider
In November, the shooting was ruled justified, the Duluth News Tribune reported.
Schneider, 31, was shot and killed by Itasca County deputy Steven Snyder after Schneider threatened deputies with a gun after they responded to an early morning disturbance call in Cohasset.
July 23, 2015: Derek Wolfsteller
The Hennepin County Attorney's Office is currently reviewing the case.
Wolfsteller was shot and killed by officer Amy Therkelsen at an Arby's restaurant in Plymouth when he tried to take the officer's gun from its holster.
May 8, 2015: Sam Holmes
In August 2015, a grand jury declined to indict Lino Lakes Sgt. William Owens on potential murder charges in the shooting death of Holmes, 31, during a traffic stop. Owens had stopped Holmes for speeding.
According to the preliminary investigation, when Owens tried to arrest Holmes for outstanding warrants and suspicion of driving under the influence, a struggle ensued. Holmes got back into his car and took off, dragging the officer.
Before falling to the roadway, Owens fired his gun at the vehicle, which left the highway, went through a fence and stopped in a nearby Cub Foods parking lot.
March 16, 2015: Justin Tolkinen
In January, a grand jury cleared four St. Paul police officers involved in the shooting death of Tolkinen, 28, after a 45-minute standoff in east St. Paul.
The Ramsey County panel concluded officers Mark Farrington, Brian Hall, Patrick Murphy and Jermaine Davis were justified in their use of deadly force. Tolkinen allegedly aimed an assault rifle at them.
Tolkinen's father told police he'd been in treatment for mental illness several times.
Jan. 26, 2015: Raymond Kmetz
A grand jury returned a no-bill, or no indictment, in the incident.
Kmetz was shot and killed after opening fire at New Hope City Hall and wounding two police officers after a swearing-in ceremony for new officers.
He had a history of confronting government and the law, and also believed that police were harassing him.
Kmetz had been in and out of the Minnesota Security Hospital in St. Peter and an Anoka mental hospital.
His son told KARE 11 that the family had grown increasingly alarmed about Kmetz's behavior.
Jan. 15, 2015: Quincy Reindl
A grand jury declined to indict Bloomington officers Jeff Bailey, Mike Perron, Mike Smith and Anthony Kiehl and an internal investigation found no wrongdoing by the officers.
Authorities said at the time that Reindl, 24, was struck by gunfire multiple times during a confrontation in January 2015. They'd been called on a report of a suicidal person at a home nearby.
Police said they found Reindl walking through the neighborhood carrying a gun, and that he'd refused orders by officers to drop the weapon.
Jan. 14, 2015: Marcus Golden
In May 2015, a Washington County grand jury declined to indict St. Paul officers Jeremy Doverspike and Dan Peck in connection to the death of Golden.
Police were called to a St. Paul apartment building on reports that Golden was making death threats. Police said Golden was in a truck in the building's parking lot and refused to get out of the vehicle. Police said Golden instead drove directly at the officers, who shot and killed him.
Police say a loaded handgun was later found within Golden's reach in the SUV.