The killings have reignited the debate about race relations in the US. Here are six surprising statistics that help tell the story.
2
black billionaires
There are only two black billionaires in the US - chat show host Oprah Winfrey and former basketball star Michael Jordan. This compared with about 500 white billionaires.
9.8%
over-25s have a degree
Black students appear to do well in high school - just over 30% of over-25s have a diploma, compared with 27% of white over-25s. But fewer than 10% of black over-25s completed a bachelor's degree, compared with 14.4% of whites.
75%
of white Americans have only white friends
A survey conducted by the Public Religion Research Institute in 2013 asked a range of questions to assess how diverse people's friendship groups were. It found that while 65% of black Americans reported only having black friends, 75% of white Americans said they had only whites in their social circle.
10.9%
black unemployment
Unemployment remains far higher among the black population, than the white. Currently 4.8% of white Americans are out of work, compared with an overall average of 5.8%
37%
male prison inmates are black
Figures based on the prison population at the end of December 2013 show black Americans made up a disproportionate number of inmates. Some 32% were white and 22% Hispanic.
Data sources: US Census, Public Religion Research Institute, Forbes, US Dept of Labor, US Dept of Justice
Correction: An earlier version of this story did not make clear that the figures for people with high school diplomas or bachelor's degrees were for those aged over 25.

Dickson, 29, made 42 appearances last season, scoring winning goals against Accrington and Mansfield as the club finished 19th in League Two.
The left-back initially signed on a one-year deal from Crawley at the beginning of the season, with the option to extend by a further year.
He told the club's website: "It would be silly not to stay on board. The club is now heading in the right direction."
Yeovil, who for a large part of the season were battling relegation, finished 14 points clear of the bottom two.
Dickson added: "Everyone at the club has worked so hard to create a togetherness and positive atmosphere, which has driven us all forward in such a short space of time."
Dickson signs a two-year deal similar to goalkeeper Artur Krysiak who put pen to paper on Tuesday, and defender Nathan Smith, 29, who signed a one-year contract extension yesterday.

A section of Victoria Pier in Colwyn Bay collapsed into the sea in February and a fire broke out there in March.
The planning and listed building consent applications have been submitted by the owners, Conwy council.
They include redeveloping a shortened pier and salvaging heritage elements of the structure for potential use in its restoration.
The Colwyn Victoria Pier Trust wants to restore the pier to its original 1900 length, complete with kiosks and a pavilion, but has recognised the remaining pier needs to be dismantled "so the community can move forward".
The 116-year-old pier was already closed to the public for safety reasons before its partial collapse.
The council said the applications would be registered by the planning authority in due course and then be subject to the usual planning process.
Once they have been considered and assessed, the listed building consent application will be submitted to the Welsh Government.
That decision will be made by a Welsh Government minister who will be advised by CADW.
In 2013, Conwy council voted to demolish the pier but this move was refused by the Welsh Government in 2015.
A white gunman shot dead nine people in an African-American church in the city of Charleston on 17 June, police say, two months after an unarmed black man was killed by a white police officer in North Charleston.
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Defender Ryan Dickson has extended his stay at Yeovil Town by two more years.
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Permission has been requested to dismantle and redevelop a Grade II-listed pier in Conwy county.