Barely 24 hours apart, the United States has witnessed two controversial police shootings of black men.

Thursday’s shooting in the state of Minnesota of 32-year-old Philando Castile, came on the heels of a similar incident in Louisiana on Wednesday in which 37-year-old unarmed father of five, Alton Sterling was shot to death at point blank range by police.

Here are a selection of killings of US black citizens that have caused outrage — and sometimes violent protests — across the world.

Amadou Diallo

The shooting of Diallo was one of the first most popular shooting of unarmed black person in America. The incident occurred on February 4, 1999, when Amadou Diallo, an unarmed 23-year-old immigrant from Guinea, was shot and killed by four New York City Police Department plain-clothed officers: Sean Carroll, Richard Murphy, Edward McMellon and Kenneth Boss. The officers fired a combined total of 41 shots, 19 of which struck Diallo, outside his apartment at 1157 Wheeler Avenue in the Soundview section of The Bronx. The four were part of the now-defunct Street Crimes Unit. All four officers were charged with second-degree murder and acquitted at trial in Albany, New York.

Thereafter, close to 10 musicians around the world, including Wyclef Jean sang about the unjust killing of Diallo.

Ousmane Zongo

Zongo was a Burkinabé arts trader living in New York City. He was killed in a homicide by a New York City Police Department officer, Bryan Conroy while unarmed, during a warehouse raid on May 22, 2003. Conroy did not receive any jail time but was convicted of criminally negligent homicide and was given five years probation, automatically losing his job with the NYPD.

Mario Woods

The scene is filmed on smartphones. At least six police agents take aim at him while he is huddled against a wall.

Freddie Gray

On April 12, 2015 Baltimore police officers arrest Freddie Gray, 25. He is handcuffed and eventually placed on his stomach in a police van, unsecured by a seatbelt.

While in transit, Gray asks for medical help but none is given. The police van is diverted to assist in an unrelated case, at which point Gray is found unresponsive.

Despite this, an ambulance is not called until after the police van reaches a police station and Gray is found to be in cardiac arrest, having suffered serious spinal injuries in the van.

Gray dies on April 19, leading to rioting in Baltimore and protests in other US cities. State prosecutor Marilyn Mosby calls the arrest illegal. Six officers are later charged over the incident. One trial ends in a hung jury, and two others in acquittal. The fourth trial started on Thursday.

Walter Scott

On April 4, 2015 in the state of South Carolina, a video shows police officer Michael Slager gunning down a fleeing black man, 50-year-old Walter Scott, after a traffic stop.

The video seems to show Slager in an altercation with Scott. Slager then draws his gun and shoot seven to eight shots in Scott’s back as he flees. Slager was charged with murder in June 2015. His trial is due to open on October 31.

Tamir Rice 

On November 22, 2014, in Cleveland, Ohio, a video emerges of US police officers shooting dead Tamir Rice, a 12-year-old black boy carrying a replica gun, just seconds after confronting him.

Surveillance video showed Rice was killed within seconds of the patrol car arriving on the scene in a park.

In December 2015, the US authorities announce that the police officers concerned will not be prosecuted.

Akai Gurley

On November 20, 2014 an unarmed black man, Akai Gurley, 28, is shot by an Asian-American officer who opens fire in a dimly lit staircase at a Brooklyn, New York apartment block.

On the day of his funeral on December 7, New Yorkers take to the streets to denounce the spate of police killings. The police officer, Peter Liang, is in April 2016 given five years probation.

Laquan McDonald

On October 20, 2014 in Chicago a white police officer pumps 16 bullets into the 17-year-old adolescent, who was not showing threatening behaviour.

Images of the incident shown in November 2015 during the indictment for premeditated murder of the police officer shocked the country.

The shockwaves led to the chief of police in Chicago being fired and a federal probe which embarrasses Chicago Mayor Rahm Emanuel, Obama’s former chief of staff.

Michael Brown

On August 9, 2014, in Ferguson, Missouri, a white police officer shoots dead 18-year-old Brown, unleashing violent protests.

A subsequent decision not to indict the officer, Darren Wilson, prompts riots in Ferguson and raises tensions from New York to Seattle, with thousands taking to the streets.

In March 2015, the US Justice Department published a scathing report into the shooting, condemning Ferguson’s city hall, police department and municipal court for targeting the city’s African American majority. A black man subsequently takes over as head of Ferguson’s police.

Eric Garner

On July 17, 2014, African American Eric Garner, 43, dies after being held in a police chokehold while he is being arrested for selling individual cigarettes illegally in New York.

In an amateur video which is viewed around the world, as police wrestle him to the ground, Garner is heard repeating: “I can’t breathe.”

A coroner declares the death a homicide. But a grand jury opts not to charge the white officer involved, sparking demonstrations in several cities.

Trayvon Martin

The 17-year-old unarmed adolescent is killed on February 26, 2012 in Sanford, Florida by neighborhood watchman George Zimmerman, who was acquitted in 2013 by a jury which found that he had acted in self defence.