By Taylor Kate Brown BBC News,
Washington
Two cases of black men being
killed in police confrontations have caused anger when no charges were brought
against the officer in each case. So when have police faced charges?
In 2013, Russell Rios, 19, fled
a Wal-mart in Conroe, Texas, after allegedly stealing about $50 (£32) in goods
from the store.
An officer, Sgt Jason
Blackwelder, responded and chased Rios on foot to a wooded area. Blackwelder
left the woods, Rios did not.
Blackwelder later said in his
report during a struggle Rios had choked him to the point of almost losing
consciousness. Blackwelder fired his gun and killed Rios, arguing it was
self-defence.
But prosecutors said evidence
from the scene contradicted that account, including the fact that Rios had been
shot in the back of the head.
Blackwelder was charged by a
grand jury for manslaughter and making false statements. He was convicted in a
jury trial.
It is one example of a rare
instance where police are arrested or charged for violent incidents related to
their police work.
"Everybody knows policing is
violent, and [jurors] don't want to second guess those decisions," says
Philip Stinson, a researcher at Bowling Green State University in Ohio and
former police officer.
Juries - both grand juries and
trial juries - tend to "give every possible benefit of the doubt"
when it comes to police officers who have killed while on-duty, Dr Stinson
says.
But the secrecy of the grand
jury proceedings make it hard to know why that was.
He adds this tendency to not
charge does not exist as strongly for police officers investigated for
non-violent crimes, including corruption cases.
Comprehensive nationwide
numbers of how many police officers kill individuals while on duty do not
exist.
The FBI does record
"justifiable homicides" by police officers. There were 461 such
homicides in 2013, but by definition, this doesn't include the number of police
charged with a crime for on-duty actions.
And reporting these statistics
to the FBI is voluntary. In addition, even police agencies who report their
overall crime numbers are not required to submit additional data on homicides,
justified or not.
Mr Stinson's own research found
41 police officers were charged with murder or manslaughter between 2005 and
2011. In the same time period, the FBI recorded several thousand justifiable
homicides.
And the process by which police
officers face charges depends on the state. Some are charged by grand juries,
others are charged directly by police through arrest warrants.
In Baltimore in 2008, Police
Officer Tommy Sanders was indicted for voluntary manslaughter while on duty
when he shot and killed Edward Lamont Hunt.
Mr Sanders told the court Hunt
had been staring at him across a car park at a shopping centre. As he was
searching Hunt, the officer said Hunt assaulted him and ran off. After giving
chase, Sanders told the court he saw Hunt reach for something.
Mr Sanders fired three shots,
two hitting Hunt in the back.
During the trial, multiple
witnesses said Hunt had never assaulted the officer, nor did he reach into his
coat while running.
How one shooting sparked a
movement
Hunt was unarmed.
While the evidence led a grand
jury to charge Hunt, he was eventually found not guilty.
But the case was slightly
different than recent cases of white police officers being accused of bias in
handling of black suspects - Mr Sanders himself is black.
And in at least one case, when
prosecutors do not get an indictment, they try again.
Last September, Jonathan
Ferrell, 24, a former college football player, was shot by Officer Randall
Kerrick as he attempted to get help after being involved a car crash late at
night in Charlotte, North Carolina.
A woman alarmed by Farrell
knocking and yelling at her door at two o'clock in the morning called police.
By the time Mr Kerrick had
arrived, Ferrell had walked away, looking for help elsewhere. What happened
next is disputed, but it ended with Mr Kerrick shooting at the 24-year-old 12
times, 10 of the shots hitting Ferrell.
Mr Kerrick's own police
department said the shooting was "excessive" and said he "did
not have a lawful right to discharge his weapon" during the incident.
Prosecutors brought the case to
a grand jury, and when they did not charge Kerrick, the state argued the jury
had not had enough people and convened a second grand jury, which did indict.
Mr Kerrick faces trial for
manslaughter next year.
And once a case goes to court,
and even a conviction, the tendency to give police officers every benefit
appears to extend to the sentencing as well.
After his conviction,
Blackwelder was given five years probation for the crime. He had faced up to 20
years based on the charge.