(CNN) Three days, three different resolutions, one common trait: white officers killing black males.

Just this week, we learned two officers will avoid federal charges in the 2016 death of Alton Sterling, a man pinned to the ground before he was shot.

Another officer has been fired for killing Jordan Edwards, a 15-year-old honor student. And yet another officer pleaded guilty after shooting Walter Scott as the 50-year-old was running away.

While officer convictions are rare, such killings have spawned " Black Lives Matter " protests and have led to notable changes -- including reforms to police policy. Here's how some of the most high-profile cases have turned out:

Jordan Edwards, 15

Date of death: April 29, 2017

Where: Balch Springs, Texas

What happened: Officers responded to a house party after reports of underage drinking. Police spotted a car leaving with five people inside -- including Jordan in the front passenger seat.

At first, Police Chief Jonathan Haber said the car was moving "aggressively" toward officers, and officer Roy Oliver fired into the car with a rifle.

But on Monday, Haber corrected himself and said body camera footage showed the car was driving forward -- away from the officers.

The outcomes: Haber fired the officer Tuesday, saying Oliver "violated several departmental policies."

Roy Oliver was fired from the Balch Springs Police Department.

Meanwhile, Jordan's classmates at Mesquite High School are grieving the loss of the beloved football player and straight-A student

Alton Sterling, 37

Alton Sterling

Date of death: July 5, 2016

Where: Baton Rouge, Louisiana

What happened: Sterling was selling CDs outside a convenience store when police received a call of a man with a gun. Cellphone video showed police tackling Sterling and pinning him to the ground before Sterling was shot. But police said Sterling was reaching for a gun.

JUST WATCHED New revelations in Alton Sterling case Replay More Videos ... MUST WATCH New revelations in Alton Sterling case 02:29

The outcomes: On Wednesday, federal prosecutors said On Wednesday, federal prosecutors said they didn't have enough evidence to file charges against Baton Rouge police officers Blane Salamoni and Howie Lake II.

Minutes later, the Louisiana attorney general announced the state will launch an investigation to see whether the officers should face state criminal charges

But Sterling's death has already yielded change. Baton Rouge Mayor Sharon Weston Broome said $2 million will be spent securing body cameras for the entire police force. On top of that, the city's police training manual will be revised, and officers will receive training in implicit bias, the mayor said.

Walter Scott, 50

JUST WATCHED Officer shoots unarmed man in the back Replay More Videos ... MUST WATCH Officer shoots unarmed man in the back 03:04

Date of death: April 4, 2015

Where: North Charleston, South Carolina

What happened: Officer Michael Slager pulled Scott over for a broken taillight. Scott bolted out of his car, though it's not clear why. His family attorney speculated that Scott's flight stemmed from his unpaid child support " Officer Michael Slager pulled Scott over for a broken taillight. Scott bolted out of his car, though it's not clear why. His family attorney speculated that Scott's flight stemmed from his unpaid child support " and a fear of maybe going back (to jail) ."

As Scott ran away from the officer, a witness captured video of Slager shooting Scott several times in the back.

The outcomes: Slager was fired and indicted for a state murder charge and federal charges, Slager was fired and indicted for a state murder charge and federal charges, including misleading investigators and excessive use of force

In exchange for his guilty plea for one of the federal counts -- punishable by up to life in prison -- two other federal charges and state charges were dropped.

Scott's death also led to a statewide change: The South Carolina Legislature passed a bill mandating the use of police body cameras.

Trayvon Martin, 17

George Zimmerman, left, and Trayvon Martin

Date of death: February 26, 2012

Where: Sanford, Florida

What happened: Martin was walking from a convenience store back to the home of his father's fiancée. Neighborhood watch volunteer George Zimmerman spotted him from his car and called 911, reporting "a real suspicious guy."

"This guy looks like he's up to no good, or he's on drugs or something," Zimmerman told a dispatcher . "It's raining, and he's just walking around."

A scuffle broke out, but there were no direct witnesses. Zimmerman claimed Martin attacked him, hitting him in the nose and knocking him onto the pavement. Zimmerman said he then took out his gun and shot Martin in self defense.

But critics said Zimmerman was unjustified in confronting the unarmed teen, especially since Zimmerman didn't heed a police dispatcher's advice to stop following him.

The outcomes: Zimmerman was charged with second-degree murder but was found not guilty. The acquittal ignited protests across the country, and Zimmerman was charged with second-degree murder but was found not guilty. The acquittal ignited protests across the country, and the "Black Lives Matter" movement gained national prominence.

The case also led to the firing of Sanford Police Chief Bill Lee , who was criticized for not arresting Zimmerman after Martin was killed.

Eric Garner, 43

An NYPD officer puts Eric Garner in a prohibited chokehold.

Date of death: July 17, 2014

Where: New York City

What happened: Police tried to arrest Garner in front of a store for allegedly selling cigarettes illegally. Garner raised both hands and told officers not to touch him. Seconds later, Police tried to arrest Garner in front of a store for allegedly selling cigarettes illegally. Garner raised both hands and told officers not to touch him. Seconds later, Officer Daniel Pantaleo grabbed the 350-pound man in a chokehold and pulled him to the sidewalk, rolling him onto his stomach.

The New York Police Department prohibits the use of chokeholds.

Garner, who had asthma, repeatedly said, "I can't breathe! I can't breathe!" while several officers restrained him on the ground. Police said he suffered a heart attack and died en route to a hospital.

The outcomes: A grand jury declined to indict Pantaleo, sparking protests and "die-ins."

Photos: Photos: Athletes wearing 'I can't breathe' shirts Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Members of the Georgetown basketball team wear "I can't breathe" shirts as they stand for the national anthem before a home game Wednesday, December 10, in Washington. The shirt references the words spoken by Eric Garner, a 43-year-old man who died earlier this year after being put in a chokehold by a New York City police officer. After a grand jury decided not to bring criminal charges against the officer, demonstrators across the country took to the streets to express their outrage. Hide Caption 1 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Portland Trail Blazers Wesley Matthews, left, and Dorell Wright wear the shirts while warming up for a game in Minneapolis on December 10. Hide Caption 2 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Kobe Bryant and the Los Angeles Lakers wear the shirts before a home game Tuesday, December 9. Hide Caption 3 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Wearing the shirts from left are Lakers Nick Young, Jordan Clarkson, Carlos Boozer, Wayne Ellington and Jeremy Lin. Hide Caption 4 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – LeBron James of the Cleveland Cavaliers wears the shirt in New York before playing the Brooklyn Nets on Monday, December 8. Hide Caption 5 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – San Diego Chargers linebacker Melvin Ingram shows his solidarity with Garner before playing New England on Sunday, December 7. Hide Caption 6 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Detroit Lions running back Reggie Bush warms up before a home game on December 7. Hide Caption 7 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Cleveland Browns cornerback Johnson Bademosi shows his support for Garner before playing a game in Cleveland on December 7. Hide Caption 8 of 9 Photos: Photos: Athletes wearing 'I can't breathe' shirts Athletes wearing 'I can't breathe' shirts – Chicago Bulls star Derrick Rose was the first major athlete to wear the shirt, making headlines Saturday, December 6, in Chicago. "I could care less about who else weighs in on this," he said. "Usually athletes tend to stay away from this, but I just felt as if I had to do something." Hide Caption 9 of 9

Garner's death also spurred a new protest slogan: "I can't breathe," referring to some of his final words before he died. Several professional athletes wore shirts saying "I can't breathe" in silent protest.

Pantaleo offered his condolences to Garner's family and said he never intended to hurt Garner. The police union defended Pantaleo, saying he just wanted to take Garner into custody after the suspect resisted.

New York City eventually settled with Garner's family for $5.9 million . City Comptroller Scott Stringer said the settlement "acknowledges the tragic nature of Mr. Garner's death," but "the city has not admitted liability."

Michael Brown, 18

Officer Darren Wilson, left, and Michael Brown

Date of death: August 9, 2014

Where: Ferguson, Missouri

What happened: Brown was walking with a friend in the middle of a street when Ferguson Police Officer Darren Wilson approached them and told them to walk on the sidewalk.

After that, the narratives split. Authorities said Brown had attacked the officer in his car and tried to take his gun. Others said the teenager was surrendering, his hands in the air to show he was unarmed, when the officer opened fire.

Documents showed that Wilson fired his gun 12 times.

The outcomes: A grand jury decided not to indict Wilson -- leading to heated and sometimes violent protests in Ferguson and across the country.

Photos: Unrest in Ferguson Photos: Unrest in Ferguson Police officers walk past the smoldering remains of a beauty supply store in Ferguson, Missouri, on Tuesday, November 25. Ferguson has been struggling to return to normal since Michael Brown, an unarmed black teenager, was killed by Darren Wilson, a white police officer, on August 9. The grand jury did not indict Wilson in the case, prompting new waves of protests in Ferguson and across the country. Hide Caption 1 of 34 Photos: Unrest in Ferguson A woman cleans up glass from a business' shattered window on November 25. Hide Caption 2 of 34 Photos: Unrest in Ferguson A Ferguson firefighter surveys rubble at a strip mall that was set on fire overnight. Hide Caption 3 of 34 Photos: Unrest in Ferguson Protesters run away after police deployed tear gas in Ferguson on Monday, November 24. Hide Caption 4 of 34 Photos: Unrest in Ferguson Police take position during clashes with protesters on November 24. Hide Caption 5 of 34 Photos: Unrest in Ferguson A protester stands in front of police vehicles with his hands up on November 24. Hide Caption 6 of 34 Photos: Unrest in Ferguson Police in riot gear move past a burning vehicle on November 24. Hide Caption 7 of 34 Photos: Unrest in Ferguson A looter in Ferguson walks out of a burning Walgreens on November 24. Hide Caption 8 of 34 Photos: Unrest in Ferguson Riot police clash with protesters on November 24. Hide Caption 9 of 34 Photos: Unrest in Ferguson Firefighters work on extinguishing a Little Caesars restaurant on November 24. Hide Caption 10 of 34 Photos: Unrest in Ferguson Smoke fills the streets of Ferguson as buildings burn on November 24. Hide Caption 11 of 34 Photos: Unrest in Ferguson Police officers grab a protester on November 24. Hide Caption 12 of 34 Photos: Unrest in Ferguson A woman treats her face for possible tear gas exposure on November 24. Hide Caption 13 of 34 Photos: Unrest in Ferguson People walk away from a burning storage facility on November 24. Hide Caption 14 of 34 Photos: Unrest in Ferguson A man steps out of a vandalized store on November 24. Hide Caption 15 of 34 Photos: Unrest in Ferguson A police officer runs by a burning police car on November 24. Hide Caption 16 of 34 Photos: Unrest in Ferguson Police officers stand guard as protesters confront them on November 24. Hide Caption 17 of 34 Photos: Unrest in Ferguson Protesters block streets in St. Louis after the announcement of the grand jury's decision on November 24. Ferguson is a suburb of St. Louis. Hide Caption 18 of 34 Photos: Unrest in Ferguson Police confront protesters in Ferguson on November 24. Hide Caption 19 of 34 Photos: Unrest in Ferguson A police officer points his rifle at demonstrators on November 24. Hide Caption 20 of 34 Photos: Unrest in Ferguson Protesters run for shelter as smoke fills the streets of Ferguson on November 24. Hide Caption 21 of 34 Photos: Unrest in Ferguson The glass windows of a store are shattered on November 24. Hide Caption 22 of 34 Photos: Unrest in Ferguson A demonstrator listens to a car radio as the grand jury's decision is delivered in front of the Ferguson Police Department. Hide Caption 23 of 34 Photos: Unrest in Ferguson Lesley McSpadden, mother of Michael Brown, is escorted away from the Ferguson Police Department on November 24. Hide Caption 24 of 34 Photos: Unrest in Ferguson A group of protesters vandalizes a police vehicle in Ferguson on November 24. Hide Caption 25 of 34 Photos: Unrest in Ferguson Police officers confront protesters on November 24. Hide Caption 26 of 34 Photos: Unrest in Ferguson Demonstrators block traffic during a protest in front of the Ferguson Police Department on November 24. Hide Caption 27 of 34 Photos: Unrest in Ferguson Demonstrators gather outside the police station on November 24. Hide Caption 28 of 34 Photos: Unrest in Ferguson Protesters gather as they wait for the announcement of the grand jury decision on November 24. Hide Caption 29 of 34 Photos: Unrest in Ferguson Members of the media line up in a parking lot across from the Buzz Westfall Justice Center on November 24. Hide Caption 30 of 34 Photos: Unrest in Ferguson Residents begin to gather at the Michael Brown memorial ahead of the grand jury announcement. Hide Caption 31 of 34 Photos: Unrest in Ferguson National Guard troops arrive ahead of the grand jury announcement. Hide Caption 32 of 34 Photos: Unrest in Ferguson Members of the Missouri National Guard are escorted out of the Buzz Westfall Justice Center. Hide Caption 33 of 34 Photos: Unrest in Ferguson Demonstrators are confronted by police as they block a street before the grand jury announcement. Hide Caption 34 of 34

A few days later, Officer Wilson resigned from the Ferguson Police Department.

Despite the lack of criminal charges, the Michael Brown case launched a series of reforms. A federal investigation revealed a pattern of abuse by Ferguson's mostly white police force against the city's majority black residents

The Justice Department found that "many officers" apparently viewed some of the city's black residents "less as constituents to be protected than as potential offenders and sources of revenue."

Black residents were ticketed and cited for minor violations at a higher rate than white residents, the Justice Department said. The investigation also found a spate of racist emails sent by some police and court officials

Freddie Gray, 25

Freddie Gray

Date of death: April 19, 2015, seven days after he was injured

Where: Baltimore

What happened: An officer on bike patrol made eye contact with Gray, and Gray fled. Police later found a knife in Gray's pocket An officer on bike patrol made eye contact with Gray, and Gray fled. Police later found a knife in Gray's pocket and arrested him on a weapons charge

Officers handcuffed Gray and put him in a police van. At some point, Gray suffered a fatal spinal cord injury. He died seven days later.

Tense moments witnessed by one photographer as protests turned to looting. #BaltimoreRiots http://t.co/in2gyPFcHo pic.twitter.com/c4krNsR9Dp — CNN iReport (@cnnireport) April 28, 2015

The outcomes: Six Baltimore police officers, including three black and three white officers, were charged in connection with Gray's death.

Photos: Baltimore officers in Freddie Gray case Lt. Brian Rice, who was part of the bike patrol that arrested Gray. On July 18, 2016, Rice was found not guilty of involuntary manslaughter, reckless endangerment and misconduct in office in connection with Gray's arrest and death. Six Baltimore police officers were charged in the April 2015 death of Freddie Gray, who died of a severe spinal-cord injury while in police custody. But there were no convictions in the case. Three of the officers were acquitted before prosecutors dropped the charges against the remaining three in July 2016 . Seen here is, who was part of the bike patrol that arrested Gray. On July 18, 2016, Rice was found not guilty of involuntary manslaughter, reckless endangerment and misconduct in office in connection with Gray's arrest and death. Hide Caption 1 of 6 Photos: Baltimore officers in Freddie Gray case Caesar Goodson drove the van in which Gray was fatally injured. On June 23, Goodson Officerdrove the van in which Gray was fatally injured. On June 23, Goodson was found not guilty on all charges, including the most serious count of second-degree depraved-heart murder. Hide Caption 2 of 6 Photos: Baltimore officers in Freddie Gray case William Porter was the first of the six officers to face a trial. It was the first of the six officers to face a trial. It ended in a mistrial in December, and he had been scheduled to be retried before prosecutors dropped the charges against him. Porter was summoned by the van's driver to check on Gray during stops on the way to a police station. Prosecutors said Porter should have called a medic for Gray sooner than one was eventually called, and they said he also should have ensured that Gray was wearing a seat belt. Porter had been charged with involuntary manslaughter, second-degree assault, reckless endangerment and misconduct in office. Hide Caption 3 of 6 Photos: Baltimore officers in Freddie Gray case Edward Nero, one of three bike officers involved in the initial police encounter with Gray, , one of three bike officers involved in the initial police encounter with Gray, was found not guilty of all charges in May. He was accused of second-degree intentional assault, two counts of misconduct in office and reckless endangerment. Hide Caption 4 of 6 Photos: Baltimore officers in Freddie Gray case Garrett Miller was another one of the bike officers involved in Gray's arrest. He placed Gray in a restraining technique known as a "leg lace" before Gray was placed in the van, said Marilyn Mosby, the state's attorney for Baltimore. All charges were dropped against Miller, who had been indicted on charges of second-degree intentional assault, two counts of misconduct in office and reckless endangerment. Hide Caption 5 of 6 Photos: Baltimore officers in Freddie Gray case Sgt. Alicia White was present during one of the stops to check on Gray's condition. She and two other officers saw Gray unresponsive on the floor of the van, and when White spoke to Gray and he did not respond, she allegedly did nothing to help him, prosecutors said. All charges were dropped against White, who had been indicted on charges of involuntary manslaughter, second-degree negligent assault, misconduct in office and reckless endangerment. Hide Caption 6 of 6

Prosecutors dropped charges against the three remaining officers : Garrett Miller; Alicia White and William Porter.

The settlement did not "represent any judgment" on whether the officers were guilty or innocent, Mayor Stephanie Rawlings-Blake said.

"This settlement represents an opportunity to bring closure to the Gray family, the community and the city."