Police Cleared More Cases When They Arrested More People

According to the Federal Bureau of Investigation’s (FBI) Criminal Justice Information Services (CJIS) division, the U.S. clearance rate for homicides—the number of murder cases considered closed or cleared for prosecution—was once an impressive 91 percent in 1965, but has since fallen to 52.3 percent.

The implication is that murders now regularly go unsolved, whereas sixty years ago almost every case was cracked. Somehow police are unable to solve more cases despite wide advancements in forensics, from DNA to digital evidence.

A whitepaper from the Department of Justice’s (DOJ) Bureau of Justice Assistance (BJA) lists various reasons why murderers are getting away with their crimes, such as an unwillingness of witnesses to come forward, the length of investigations, and the importance of the first 48 hours after the event.

But witness cooperation and time have always been an issue for homicide investigations. One aspect that is not mentioned in the paper is that police previously arrested many more suspects than they do now, more than the number of homicides.

Based on data from the DOJ’s Office of Justice Programs (OJP), arrest rates before 1991 were consistently higher than homicide rates. That is, more people were being arrested for murder than there were people being murdered (arrest rates and homicide rates are based on the total U.S. population).

Back in 1969, the arrest rate for homicide was 159 percent—police were arresting 1.59 people for every murder. In the 1990s, they were about equal, but since then they have diverged with fewer and fewer arrests, leading to the growing unsolved murder rate.

Arrest rates were also higher than clearance rates. More people were arrested than cases closed. But since the 1960s, the two have effectively converged, so each arrest is now equivalent to a closed case.

Essentially, police departments have become more accurate but potentially less effective.

Defining Clearance And Arrest

Often arrests are considered synonymous with a case being closed or cleared and charges being brought, but not necessarily.

For example, somebody can be temporarily arrested but then released if there’s not enough evidence to bring charges. Multiple people can be temporarily arrested for the same crime before a charge is brought.

According to a 2024 paper in Annual Reviews, clearance can either mean a case is cleared by arrest—arrested, charged, or turned over to the courts—or clearance by exceptional means—a case is solved without arrest, like the death of the suspect. Clearance by exceptional means only accounts for “one in nine homicide clearances in recent years.”

A 2000 paper by researchers at the University of Maryland, Clearing Up Homicide Clearance Rates, defines a closed case as one that includes either an arrest, murder/suicide situation, or self-defense. In that review, arrests still account for the vast majority of cleared or closed cases.

An arrest warrant was issued and the suspect was arrested in 80 percent of the closed cases. In the remaining closed cases, the suspect was already in custody (17 percent), the homicide was a murder/suicide (2 percent), or the homicide was in self-defense (1 percent)

Clearances are not always one-to-one with murders, as in the case of one suspect responsible for multiple homicides.

There might be some discrepancy as to how arrest is defined—arrests that led to charges versus arrests that didn’t.

For example, in 1980, when the national arrest rate for homicide was over 100 percent, New York City had 1,821 homicides, and 1,167 arrests—a 64 percent arrest rate—according to a report from OJP. Either the largest American city with one of the largest murder rates at the time was an anomaly or they might only be counting arrests that led to charges and a case cleared.

Chicago’s High Arrest Rate

That Annual Reviews paper, while skeptical of the clearance rate decline, does believe the declining clearance trend to be accurate because of research from another paper, Homicides in Chicago, 1965–1995. That paper documents an even starker decline for the windy city than the national rate, going from 91 percent in 1965 to 57 percent by 1994.

Annual reports from the Chicago police department confirm that clearance rates were indeed high, like this one from 1965 listing an impeccable clearance rate of 93.9 percent.

But unlike the New York City numbers, the number of arrests were more than the number of murder cases, similar to the national rate.

There were 480 arrests for murder and non-negligent manslaughter in 1965 when there were 395 murders—as if the police department regularly arrested multiple people for the same homicide case.