Six serial killers who were never caught

We don't even know the faces of these notorious, mysterious figures, let alone their real names.

Jack the Ripper

Let's start with the most famous serial killer of all time, Jack the Ripper. This murderer operated in the Whitechapel area of London, England, in 1888 and is credited with at least five victims, though more (or even fewer) is possible. His main targets appeared to be prostitutes. It has never been fully confirmed, but several letters sent to London police were said to have been from Jack the Ripper, though the veracity of these letters has often been questioned. Similar murders, showing a penchant for mutilation and butchery, against prostitutes had happened in London before 1888 and continued on later, though none of those have been directly linked to this killer. Numerous suspects have been named as Jack the Ripper over the years, though the truth remains unknown more than a hundred years later.

The Zodiac Killer

Like the others listed here, the identity of this serial killer has never been known for sure, though there has been at least one strong suspect who died in 1992. The Zodiac Killer was active in California in the late 1960s through the mid-1970s. He killed at least five people, though in letters to police and the media, he claimed to have killed many more. Two of his victims survived, though none could ever tell police who the killer was, though there were some basic descriptions offered. During one attack, this killer was known to have worn a bag over his head, making identification difficult. He also played a cat-and-mouse game with law enforcement, mailing cryptic notes and coded letters to police, newspapers and television stations. Police at the time also thought it possible the Zodiac Killer took credit for disappearances and murders of which he was not truly connected. The final murder count will likely never be known.

Cleveland Torso Murderer

Between 1935 and 1938, 12 to 15 murder victims are suspected of having been killed by the Cleveland Torso Murderer, who received his name because he usually dismembered his victims. There has been some evidence and speculation that similar killings were going on as early as the 1920s and into the 1950s in the northern Ohio region (and some in Pennsylvania), but none of these others have definitively been tied to this one killer. Of those thought to have been slain by the Cleveland Torso Murderer, 12 are considered definite victims of this killer, while others are still somewhat questionable. Only two of the victims have ever to be identified. There have been two suspects tied to these murders. The first one was arrested by law enforcement officers and died in jail, police brutality being suspected. The second, and arguably stronger, suspect was a doctor who was institutionalized in 1938 and died in a hospital in 1965; this doctor was known to have been a member of a medical unit that performed amputations during World War I.

Axeman of New Orleans

This serial killer was active in and around New Orleans, Louisiana, in the years 1918 and 1919. His victims are numbered at 12. He first attacked a sleeping couple in their home on May 12, 1918, killing both, and then continued apparently at random to kill with an ax until mysteriously stopping in October of 1919. Mystery has always surrounded this serial killer, and continues to do so. Some eyewitnesses thought they saw more than one possible suspect at the scene. There were also a few hints of organized crime being involved, especially since the Axeman's early victims were Italian-Americans. Then there's also the odd letter on March 13, 1919 that was supposedly from the Axeman and arrived at the local newspapers; the letter stated that the Axeman would kill again at 15 minutes past minute on the night of March 15, 1919, but would spare any New Orleans households where jazz music was playing. Newspaper reports from the time say that March 15 was filled with jazz music all over the town, and no one was murdered. There has never been a solid suspect or suspects in the case of the Axeman of New Orleans.

Phantom Killer

The murderer dubbed the Phantom Killer first struck in Texarkana, Texas, on February 23, 1946, attacking a young couple in a vehicle, but killing neither. From then until May 4 of that year, at least five people were killed and three others attacked. All are alleged to have been victims of the Phantom Killer. Who was this murderer? It is still not known. On May 6, a man's mutilated body was found on railroad tracks near Texarkana, and some believed he might have been the killer even though a coroner reported the man had been stabbed repeatedly before coming to rest on the tracks. Another suspect was a small-time burglar and car thief, though no strong evidence was never found against him. It has been so long, it is not likely the Phantom Killer is still alive.

Phantom of Heilbronn

This is the only female killer to make this list, and it's only hypothesized that's she's a she, and it's also possible she might not even exist. The Phantom of Heilbronn is the given name for an unknown assailant who shot and killed a female police officer in Heilbronn, Germany, in 2007. DNA evidence has linked this mysterious killer to possibly as many as 60 other crimes, at least six of them murders, in Germany, Austria, France and possibly other parts of Europe. Most recently, in March 2009, police investigators came to a surprising conclusion: the so-called Phantom of Heilbronn doesn't exist at all. How could this happen? Supposedly the cotton swabs used by police to collect DNA evidence were contaminated before being shipped to law enforcement, which could explain the same DNA being found at so many crime scenes. Still, there are those who are skeptical and believe a female killer is still on the loose in Europe and has been operating since the early 1990s.