LOUISVILLE, Ky. >> Someone murdered Raymel Atkins in Louisville, Kentucky, in 2023. More than a year later, his mother and sister don’t know who did it; the police have not made an arrest in the case. The same is true for Tiffanie Floyd, killed in 2021. And Michael David in 2017. And Cory Crowe, killed in 2014.

In fact, the Louisville police do not arrest anyone in roughly half of murder cases. I spoke to family members of a dozen victims. They all conveyed a similar sentiment: police had abandoned them and theirs. “The police don’t really care,” said Deondra Kimble, David’s aunt. “They’ve proven it to me.”

Louisville’s police department acknowledges serious problems; it says it is about 300 officers below full staffing. The department is trying to address those issues, said Jennifer Keeney, a spokesperson. She shared a message for the family members of murder victims: “We understand they are grieving, frustrated and in pain. We want them to know it’s frustrating for us, too, and that we do care.”

Louisville is representative of a national issue. In the United States, people often get away with murder. The clearance rate — the share of cases that result in an arrest or are otherwise solved — was 58% in 2023, the latest year for which FBI data is available. And that figure is inflated because it includes murders from previous years that police solved in 2023.

In other words, a murderer’s chance of getting caught within a year essentially comes down to a coin flip. For other crimes, clearance rates are even lower. Only 8% of car thefts result in an arrest.

Compared with its peers, America does an unusually poor job of solving killings. The murder clearance rates of other rich nations, including Australia, Britain and Germany, hover in the 70s, 80s and 90s. Several issues, including a lack of resources, the sheer volume of cases and a distrust of the police, have converged to make the jobs of American detectives much more difficult. “It’s a serious problem,” said Philip Cook, a criminal justice researcher at Duke University.

The lack of legal accountability emboldens criminals, leading to more crime and violence.

“It’s a vicious cycle,” Brian Forst, a criminologist at American University, told me. “When the bad guys see that the police are not there to deter crime and catch criminals, they remain on the streets to do more bad stuff. And the rest of the community is less deterred from crime. They think, ‘Why not? I’m not going to get caught.’”

Many things lead someone to commit a murder, but one factor is whether murderers are caught after the act. First, a locked-up killer can’t kill more people, which is what criminologists call an incapacitation effect. Second, the act of catching a murderer deters would-be killers.

In the 18th century, Italian criminologist Cesare Beccaria devised the deterrence theory that criminal justice systems have depended on since. He cited three primary principles to deterrence: the severity of a punishment, the speed at which someone is captured and the certainty he or she will be found.

American policy often focuses on severity. In recent decades, lawmakers responded to spikes in crime by increasing the length of prison sentences. They paid less attention to the certainty and swiftness of punishment. Yet those two other factors may matter more to deterrence, some experts say. If people don’t believe the police will catch them — and quickly — then the length of punishment won’t matter.

“The certainty of being caught is a vastly more powerful deterrent than the punishment,” concluded the National Institute of Justice in its review of the evidence.

Why does America solve so few crimes? Experts point to five explanations.

1. lack of attention and resources >> We can solve difficult cases. Indeed, studies show that police departments solve more murders and shootings when they spend more time and money on them. One program in Boston, which revised procedures and boosted resources for homicide investigations, led to a 23% increase in clearance rates. The New York Police Department has one of the best-funded and staffed police departments in the country, and it consistently reports higher clearance rates than other major cities. But departments and lawmakers have for decades focused on proactive strategies, such as flooding neighborhoods with police officers, that emphasize stopping crime before or as it happens. Those strategies can work to combat crime, studies have found. But they don’t have to come at the cost of the other side of policing: catching criminals after the act.

2. Guns >> America has more firearms than any other country, and these weapons make it easier to get away with murder. A drive-by shooter can ride off before anyone sees his face, making it easier to kill anonymously. Killing another person with a knife, on the other hand, “is a pretty intimate act that is likely to generate more and different kinds of evidence,” Cook, the Duke researcher, said.

3. types of crime >> The U.S. has more gang crime than other rich countries, and it’s harder to solve. A personal crime involves people with more history. A husband who kills his wife has a legal relationship with her, easily found in court records. Family members know the killer and victim intimately. That is less likely for gang crimes; a gang member who kills a stranger in a carjacking gives the police less to work with. Gang members also work together to get away with crimes, and potential witnesses are often scared to testify against them.

4. Volume >> The U.S. has far more murders and fewer police officers, after controlling for population, than other rich countries. The number of cases overwhelms the police. A detective who deals with only one murder per year gets much more time on the case than a detective who deals with one per week. “We’ve gotten swamped,” said Emily McKinley, a deputy police chief in Louisville who previously worked as a homicide detective. “Violent crime, we’ve lost control of it.”

5. Distrust of police >> High-profile deaths and protests have exposed abuses in police departments. Detectives rely on witnesses to solve crimes. But “citizens are not going to want to cooperate with the police when they see the police as alien storm troopers,” Forst said. They also are less likely to cooperate if they believe police can’t or won’t protect them from a crime suspect’s retaliation.