It is hard to know the number of serial killers which may be out there at any given time. The FBI estimates there are somewhere between 20 and 50 unidentified serial killers who are active. Serial killing is not a modern phenomenon, and serial killers have been responsible for murders in all parts of the world. The idea of an individual preying on other humans is a frightening thought. What is even more disturbing is some serial murder crimes remain unsolved, such as those listed below.

Jack the Ripper

Probably one of the most famous serial killers in history, Jack the Ripper has been written about for centuries. Jack the Ripper is thought to be responsible for several killings in the Whitechapel area of London in the late 1880s. Usually the killer’s victims were prostitutes whose throats were slit. One particularly gruesome aspect of the murders was the fact the killer removed the abdominal organs from some of the victims. Because of the removal of internal organs, some theorized a doctor or other medical professional was responsible for the murders. Although hundreds of people were interviewed and investigated, no arrests were ever made.

Zodiac Killer

In Northern California from 1968 to the early 1970s, a deranged individual, who named himself the “Zodiac” terrorized the community. The Zodiac Killer is thought to have murdered at least 5 people, but has claimed to have killed dozens more. The murderer shot or stabbed his victims. The killer sent letters to several northern California newspapers in which he boasted about the killings and referred to himself as the Zodiac. At the time, the Zodiac had written information about the murders that the police had not released to the media.  Although there were plenty of suspects, the case of the Zodiac Killer remains unsolved.

Tylenol Murders

Although it may not be thought of as typical serial murder case, in the fall of 1982, the Tylenol murderer was responsible for the deaths of seven people. The victims died after taking Tylenol, which had been laced with cyanide. All of the victims lived in the Chicago area. It was found the bottles of the pain reliever were manufactured in different facilities so the poisoning could not have taken placed during production. Investigators believe the killer went into stores, tampered with the bottles and placed the poison. No suspects have been arrested in the Tylenol murders, and the case remains unsolved. The murders did cause manufacturers of various products to develop new ways of packaging to identify if a product has been tampered with.  

The Capital City Murderer

The Capital City Murderer may not be as well-known as other serial killers, but the same killer is thought to be responsible for the murders of eight women who were associated with the University of Wisconsin. The murders took place between 1968 and 1984. Investigators believe one person is responsible for the murders due to the similarities in the cases. For instance, all the victims were young women with long hair parted on the same side. There were also similarities in where the victims were found. The murders stopped in 1984, and no one has ever been arrested for the crimes.

What drives someone to become a serial killer has been and will continue to be studied for years to come. Why serial murderers stop committing crimes is also unknown. Some theories include the killer is arrested for something else, died or moved to another area. What remains chilling is serial murderers, such as those above, are not always caught, and the cases remain unsolved even after the best efforts of criminal justice program graduates.

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