10 Unsolved Serial Killer Cases That Left Us Puzzled

It can sometimes seem as if the United States has the highest crime rate in the world, partly because it does have the highest rate of gun ownership and the largest prison population. However, when it comes to violent crime, the U.S. does not rank among the top 10 countries worldwide. That is not to say crime is not a serious issue, but levels vary greatly by region. According to the FBI, a violent crime occurs about every 24.6 seconds, and a murder takes place roughly every 30.5 minutes. With that frequency, it is not surprising that many cases remain unsolved, including some of the most baffling serial killer investigations in history.

In 2017, the FBI's Uniform Crime Report showed that law enforcement cleared 61.6% of murders, which means nearly 4 in 10 homicides went unsolved. The FBI has also estimated that at any given time, there may be about 50 active serial killers in the United States. Still, violence and serial murder are not problems limited to America. Countries around the world have their own grim histories of unsolved serial killings.

To put together a list of some of the most puzzling unsolved cases, 24/7 Tempo reviewed both well-known and lesser-known examples. We researched each killer and the crimes linked to them. While serial killings account for less than 1% of all murders in the United States, the fact that about 40% of homicides remain unsolved raises troubling questions. It also underscores how limited the available data on serial killers has become, especially in more recent decades.

The canonical five were Mary Ann Nichols, found August 31st, Annie Chapman, found September 8th, Elizabeth Stride, found September 30th, Catherine "Kate" Eddows, also found September 30th, and Mary Jane Kelly, found November 9th. In each instance, the victim's throat was slit, and the body was viciously mutilated in such a way that made it clear that the killer had some present knowledge of human anatomy. In one instance, half a human kidney was mailed to the police, presumably from a victim. Additionally, the authorities received several letters claiming to be from the killer, taunting them and referring to themselves as "Jack the Ripper," from which the case derives its name.

There are a few substantiated suspects in the case, although no one was ever definitively confirmed as the killer. Firstly, there is Montague Druitt, a local barrister who had an interest in surgery. He disappeared and was found dead shortly after the final killings. There is also Michael Ostrog, a Russian criminal and physician who was hospitalized in an asylum due to homicidal tendencies. Aaron Kosminski was implicated due to his hatred for women, especially prostitutes, and was hospitalized after the final murders.

The first murders that were definitively tied to the Zodiac Killer were those of a teenage couple in 1968. They were shot to death near their car in a remote area near San Francisco. Another couple in 1969 was attacked under similar circumstances. However, in this case, the male victim survived. Following this attack, the killer phoned the cops to confess to both the 1969 and 1968 attacks. Finally, the last known victim of the Zodiac Killer was a taxi driver, who was shot to death in October 1969. While some historians believe that the Zodiac continued to be an active serial killer after this, no airtight proof has tied him to any murders in the following years.

What makes the Zodiac Killer so well-known is the number of taunting letters and phone calls he made to the police regarding his crimes. Among these were four ciphers or cryptograms that began with "This is the Zodiac speaking," and ended with a signature symbol that appears to be a pair of crosshairs. His ciphers included chilling statements such as "I like killing people because it is so much fun." and "I hope you are having lots of fun trying to catch me."

There were at least 150 young men in Adelaide who were drugged and raped, often by multiple men, during the Family's active years. However, five of those men were also murdered. These five young men were kept captive for upwards of five weeks. During this time, they were repeatedly drugged, raped, tortured, mutilated, and ultimately killed. The five who never made it home were Alan Barnes, Neil Muir, Richard Kelvin, Peter Stogneff, and Mark Langley. Many of the victims were seen with Bevan von Einem or people who knew him before they disappeared.

While many people in von Einem's social circle have been implicated in the murders, only von Einem was convicted. He was originally sentenced to a 24-year non-parole prison term, which was extended to 36 years. He was later given an additional three months in prison when he was found with handwritten stories about having inappropriate relations with boys and men, which he claimed he kept as "insurance" against another prisoner who had made threats about him. His fingerprints were not found on any of the pages and they were kept in a sealed envelope in his cell.

While many of the key figures in the Doodler case have since passed, including the original detective who oversaw the investigation, new evidence has recently been unearthed that may lead to answers in this cold case. However, the evidence may lead to something less satisfying: a dead person. As the case has been cold for almost fifty years and many of the witnesses have also passed, the Doodler may be also no longer among us.

While that would mean that, at a bare minimum, people are safe from him, it may be unsatisfying to the victims' loved ones to know that he had lived a full life after claiming the lives of others.Police hope that the DNA technology they are currently using to re-open the Doodler's case might also lead them to the identity of the Zodiac Killer.

Several convictions were made in conjunction with the case, the most notable being that of Stefano Mele, the first female victim's husband, and Pietro Pacciani, a farmer who was convicted of seven out of eight killings. However, Pacciani's initial trial was deemed invalid, and he died before a second trial could be conducted. New evidence may reopen the case. Prosecutors now believe that Pacciani wasn't acting alone. He had been working with his friends Mario Vanni and Giancarlo Lotti to kill these couples. Five different men have been imprisoned at one time or another for the murders. However, they were subsequently released when more killings occurred during their confinement.

One suspect that investigators think was inadequately questioned was Giampiero Vigilanti, a close friend of Pietro Pacciani. Looking through his house, police uncovered a gruesome obsession with the Monster of Florence killings. He had newspaper clippings and bullets of the same type used in the murders.

Discoveries involving the Butcher of Mons began on March 22nd, 1997. A police officer came across nine garbage bags containing human remains near the Rue Emile Vandervelde in Cuesmes. The bags and contents were examined by a magistrate. It was determined that the body parts came from three different bodies, all women. Of the nine bags, five were determined to have come from the Knokke-Heist municipality. Another bag was found on the same street the following day. A tenth bag was discovered on the chemin de l'Inquiétude in Mons on March 24th. Two more bags were found on April 12th in the rue du Dépôt near the Haines River.

Several people were considered persons of interest during the investigation of the murders. The most notable was Smail Tulja. He was arrested in Montenegro under suspicion of having killed his wife in New York. He was also suspected of two murders in Albania. However, he was not extradited due to his citizenship and was tried and sentenced in Montenegro. He is reported to have died in prison in February of 2012. His involvement in the murders in Albania and Belgium was never confirmed.

Portugal's Judicial Police opened an official investigation into the case following the killing of Maria Fernanda, the second victim. A team of six men worked 24 hours a day on the case, sometimes with help from the drug trafficking division. They had suspects, but no evidence, as investigation of the crime scenes yielded few conclusive leads, such as fingerprints, hair samples, or footprints.

In 2011, a young man named Joel entered the Portuguese reality show, Secret Story: A Casa dos Segredos 2, with the secret "I am the son of the Lisbon Ripper." Before they could arrest his father, José Pedro Guedes, he confessed to some details of the case to the online edition of the Sol newspaper. Due to Portugal's statute of limitations being 15 years for murder, he could not be tried for the killings.

Despite this, the PJ arrested him under suspicion of killing Filipa Ferreira in 2000. He was cleared of suspicion of the Lisbon Ripper killings when his telling of the story didn't match the evidence in the case. His palm print was compared to one left by the Ripper on a milk carton, and they did not match.

After the death of the seventh victim, a witness came forward. He claimed to have had sex with a man named Roman. The witness met up with Roman and went to the victim's apartment. When the rest of the guests left, Roman stayed behind with the victim. The next day, the victim was found dead. The witness claimed that Roman had told him a lot about himself. He'd claimed to have been raped by an educator at a reformatory when he was 15.

He also said he worked in the Inuit cotton industry and lived with his mother near Rzgowska Street. He also said he had several tattoos, including a dot near his left eye, a laryngeal dot, and letters on his fingers on his left hand. Despite this evidence, no arrests were made, and the case remains cold.

The ninth child to disappear, Rachid Bouzian, was abducted on August 8th, 1990, and found dead the next day. On August 23rd of the same year, a man connected to the incident was apprehended. He accused his brother of the abduction and murder, but he had already fled the country. The initial suspect was found guilty of abduction and murder and sentenced to life in prison, where he eventually died.

The tenth and twelfth children, Sarah Siad and Saïda Berch, were solved when DNA evidence at the crime scene implicated a man who was in the French national DNA database for driving under the influence and driving without insurance.Though the above three murders were solved, the other nine remain without leads. In 2008, the French authorities created a unit known as Mineurs 38 (Minors 38—38 being the French code for the Isère area) to investigate the remaining cases.

All five of the missing girls were aged four to eight, three disappeared from pachinko parlors, three were dumped near a river (in two cases, the victims were found near the Watarase River), and four of the cases occurred on a Friday, weekend, or holiday. Security footage of the culprit from the 1996 kidnapping exists. Additionally, DNA tests prove a 100% match to the Ashikaga case. However, despite this, no arrests have been made, and the cases remain unsolved.

Shimizu discovered that the DNA testing initially done in the Ashikaga case was grossly flawed. The same type of testing was done in the Iizuka case. In that case, the alleged perpetrator had requested new DNA testing to be done and a retrial. He was not only denied but also executed. Thus, acknowledging the flaws in the test would cause a scandal in both cases. He posits that the authorities attempted to hide the flawed tests by arresting an innocent man.