What makes a serial killer? While that’s a provocative question, I mean it here in the most literal sense: What, exactly, is the definition of a serial killer and at what point does a murderer gain the specter of a serial killer?
In 1998, the US Congress passed a federal law protecting children where it defined “serial killings” as a “series of three or more killings, not less than one of which was committed within the United States, having common characteristics such as to suggest the reasonable possibility that the crimes were committed by the same actor or actors.” This definition has become the general standard, though other definitions have given a different minimum number of victims. The FBI held a Serial Murder Symposium in 2005 which defined serial murder as only needing two or more victims killed by the same offender(s). Thus, there’s no officially agreed-upon definition, but either two or three seems to be the most common minimum number. To further muddy the waters, some definitions include timeframes. Wikipedia, for example, reports that the murders need to take place over more than a month and must include a significant amount of time between them.
We know that serial killers are not a new phenomenon. In fact, one of the oldest and most notorious serial killers, Jack the Ripper, was active in the 1880s. But the term “serial killer” is considered to be relatively recent. In 1970, a man named Robert Ressler joined the FBI with the intent on researching and understanding extremely violent cases where motive seemed difficult to pin down. While with the FBI, he and Special Agent Roy Hazelwood helped pioneer modern criminal profiling. They applied methods of criminal profiling to research serial killers—and Ressler was the first to coin the term. It’s possible that his fascination with serial killers arose simply because they were a part of the zeitgeist. After all, he joined the FBI amidst the so-called “Golden Age of Serial Killers” of the 70s and 80s in the US. Perhaps it was the need for a term that reflected the phenomenon that spurred its invention.
While Ressler is often cited to be the first person to coin the term “serial killer,” the claim is disputed. There are others who have been credited with the first use of the term. Some people believe that Pierce Brooks, an LAPD detective, was the first person to define the term, if not use it. Prior to that, people have pointed out the term “serial murder” appears in a book from 1950 by Richard Hughes entitled The Complete Detective. There are also a few other places where the term may have appeared, the earliest source found so far is from the 1930s. Ernst Gennat was the director of the Berlin Criminal Police who headed a workforce dedicated to solving homicides. In his 1930 article, “Die Düsseldorfer Sexualverbrechen” about a German serial killer, he used the German term “Serienmörder.” In its English publication, it was translated as “serial murderer.” Regardless of its first use, the term was popularized by a report from The New York Times in 1981 that covered Wayne Williams. Throughout the 1980s, the paper used the label around 200 times—but by the end of the 1990s, it had increased to 2,500 instances.
What is clear is that a term was sorely needed as incidents of serial killings started to rise to unprecedented numbers in the US during the 1970s and 1980s. It was important to distinguish their methodology and motives (or a seeming lack thereof) from other crimes of a similar nature. Even if Ressler didn’t coin the term, he knew that understanding how these types of killers operated could help connect, solve, and hopefully prevent future cases.