4. Jack the Stripper
Jack the Stripper was the nickname given to an unknown serial killer responsible for what came to be known as the London “nude murders” between 1964 and 1965.
His victimology was similar to Jack the Ripper's. He murdered six, possibly eight, prostitutes, whose nude bodies were discovered around London or dumped in the River Thames.
The victim count is ambiguous because two of the murders attributed to him did not fit his modus operandi. Like the Jack the Ripper killings, the Stripper's reign of terror seemed to cease on its own, and there were few solid clues for police to investigate.
Though his identity remains unknown, crime writer Donald Rumbelow notes that the killer could have been a young man who committed suicide in south London.
This main suspect, who was also a favorite suspect of Chief Superintendent Du Rose, was a security guard on the Heron Trading Estate in Acton whose rounds included a paint shop where one of the bodies was thought to have been hidden after the crime.
Though there was never any hard evidence to link him to the crimes, his family found his suicide inexplicable, and his suicide note cryptically said only that he was “unable to take the strain any longer”.
4. The Axeman of New Orleans
On May 23, 1918, an Italian grocer named Joseph Maggio and his wife were butchered while sleeping in their apartment above the Maggio grocery store.
Upon investigation, the police discovered that a panel in the rear door had been chiseled out, providing a way in for the killer.
The murder weapon, an axe, was found in the apartment, still coated with the Maggio's blood. Nothing in the house had been stolen, including jewelry and money that were nearly in plain sight.
The only clue that was discovered was a message that had been written in chalk near the victim's home. It read: “Mrs. Joseph Maggio will sit up tonight. Just write Mrs. Toney”.
Almost exactly a month after the Maggio murder came a second crime. Louis Bossumer, a grocer who lived behind his store with his common-law wife, Annie Harriet Lowe, was discovered by neighbors one morning, lying in a pool of blood.
The Axeman murdered a total of eight people before the killings stopped. There was no evidence to link the only suspect, Joseph Mumfre, to the crimes.
5. JonBenét Ramsay
JonBenet Ramsays was a six-year-old girl known for her participation in beauty pageants in the United States.
She was found murdered in the basement of her parents' home in Boulder, Colorado, nearly eight hours after she was reported missing.
The case is notable in both its longevity and the media interest it has generated in the United States. After several grand jury hearings the case is still unsolved.
In December 2003, forensic investigators extracted enough material from a mixed blood sample found on JonBenét's underwear to establish a DNA profile.
The DNA belongs to an unknown Caucasian male. The DNA was submitted to the FBI's Combined DNA Index System (CODIS), a database containing more than 1.6 million DNA profiles, mainly from convicted felons.
The sample has yet to find a match in the database, although it continues to be checked for partial matches on a weekly basis.