The job of the South African police is to fight one of the highest crime rates in the world. Instead, the force stands accused of contributing to it.
The release of a video showing uniformed police binding a taxi driver to the back of a police vehicle and dragging him - the man was later found dead in a police cell - shocked South Africans long accustomed to stories of police misconduct.
At a bail hearing for Oscar Pistorius last week, a magistrate harshly criticized a police detective for shoddy work in the investigation into the murder case against the double-amputee athlete, who is charged with killing his girlfriend.
And last year, police fired into a crowd of striking miners, killing 34 in a convulsion of violence that reminded many of the worst excesses of the apartheid era.
These high-profile episodes cap a steady flow of allegations of police misconduct, whether in top rank corruption, prosecutions of officers charged with murder and rape, or numerous anecdotes of police pulling over drivers and demanding bribes.
Many South Africans mistrust the very institution that is supposed to protect them, and the scandals weaken efforts by South Africa to project itself as a model country and a leader by example in sub-Saharan Africa.
"They are there for safety, but we as a people fear them more," said Alfonso Adams, a resident of Johannesburg.
"You don't know who to trust anymore."
The Daily Sun, a South African newspaper, posted footage of the dragging incident, which occurred on Tuesday and was apparently filmed by several people using cellular telephones.
By some accounts, taxi driver Mido Macia, 27, of Mozambique drew the attention of police when he parked in a way that blocked traffic, and then got into an altercation with officers.
"We are going to film this," several onlookers shouted in Zulu as the police roughly subdued Macia. One bystander can be heard shouting: "What has this guy done?"
It remains to be seen whether the succession of scandals will trigger such a groundswell of public outrage that the government will push through reforms to the troubled police.
Rape has been a scourge of South African society for many years, but sexual violence remains endemic despite periodic outcries.
In the case of the taxi driver who was dragged behind a police van, officers paid little heed to the crowd that gathered, suggesting a sense of impunity has taken hold in police ranks.
President Jacob Zuma condemned the killing of Macia, who died from head and other injuries after he was dragged in Daveyton, a township east of Johannesburg.
Some commentators drew comparisons with the 1977 death of anti-apartheid activist Steve Biko, who also suffered head injuries in police custody.
"Members of the South African police service are required to operate within the confines of the law in executing their duties," Zuma said in a statement.
"The visuals of the incident are horrific, disturbing and unacceptable. No human being should be treated in that manner."
Brigadier Phuti Setati, a police spokesman, told South Africa's Radio 702 that no police had yet been suspended, but said all crimes should be investigated, "irrespective of who is involved."
Johan Burger, a former police veteran and a senior researcher at the Institute for Security Studies in Pretoria, said the force rapidly expanded from 120,000 to almost 200,000 over the past decade, largely neglecting the quality of personnel that it recruited.
Two police chiefs lost their jobs; one was Jackie Selebi, given a 15-year prison sentence for corruption after he went shopping with a drug smuggler in exchange for information.
Selebi was later released on medical grounds.
''It is a crisis that starts at the top and filters down and it has a huge impact on morale of police on the ground," Burger said, adding that reforms to the police would be a hard, lengthy process.
''It is like trying to fix a runaway bus going downhill," he said.
Police said National Police Commissioner Riah Phiyega planned to hold a news conference on the dragging incident.
She was brought in to lead the police as an outsider with a social science and business background, and is the first woman to lead the force.
She removed chief investigator Hilton Botha in the Pistorius case after he made a number of errors in the investigation, and after it was revealed that he faced attempted murder charges stemming from a 2011 incident in which he and two other officers allegedly shot at a minivan while trying to stop it.
''Embarrassing? There is nothing embarrassing for us as the police," Phiyega said. ''I am not a judge. We are not magistrates. We cannot say it was a sterling performance, not a sterling performance."
Pistorius, who was released on bail, said he accidentally shot and killed his girlfriend, Reeva Steenkamp, mistaking her for an intruder.
Prosecutors say he killed her intentionally after the couple had an argument.
Botha's missteps included misjudging distances, neglecting to wear protective covers while on the crime scene and failing to push for cellular telephone records that would bolster the state's case.
''It is absolutely par for the course," said Nooshin Erfani, the coordinator of Wits Justice Project at Witwatersrand University.
''Such ridiculous things happen all the time."
South Africa is also struggling with the fallout from the Marikana mine shootings.
On August 16, 2012, a line of South African police opened fire on striking miners, killing several dozen at a platinum mine northwest of Johannesburg.
Now a judicial commission is investigating allegations that many were shot in the back as they tried to escape.
''That is a kind of a huge scar on our national psyche," Erfani said. " All of these issues now place even more of a strain on the credibility of the police."
South Africa's high crime rate has fed a gun culture that feeds off the perception that police cannot be trusted to do the job. In a country of 49 million, 15,609 were murdered over the last year.
"They are no deterrent or help," Sheila Rosslee said of South African police. Her husband owns a gun range and is a firearms instructor in eastern Pretoria.
In 2007, she fired two shots at two men who pulled guns on her, slightly wounding one. Even though she gave the police her address and phone number, she said: "They couldn't even be bothered to contact me."
Police, too, are victims.
On January 27, which was designated National Police Day, the government and families of slain officers paid tribute to the "fallen heroes" of the police forces at a monument in Pretoria. Nathi Mthethwa, the minister of police, said 92 police were killed, mostly at hands of criminals, between March 2011 and April 2012.
So the distrust of police inherited from the days of white racist rule, when officers were tools of state-sponsored violence, endures almost two decades after Nelson Mandela became South Africa's first black president.
''What used to work in South Africa before was violence," Erfani said. ''Whatever colour spectrum you were at, it was a successful way of dealing with issues."
A look at a recent five-day span of cases posted by the Independent Police Investigative Directorate, a watchdog agency, spells out the problem.
''Constable appears in court for rape," says one entry. ''Constable convicted of murder for shooting 15 year old," says another. A third reads: ''Constable sentenced to 15 years for murdering his girlfriend."