Is there anything more chilling than the thought of a crime so heinous and brutal, yet so marvelously crafted and baffling, that it remains forever unsolved? Top investigators, countless numbers of law enforcement officers, and piles upon piles of tangible clues and possible subjects, but a mystery remains impervious to all efforts. If you're interested in pondering some of the most enigmatic and inexplicable crimes of our time, the following murders are certainly a good place to start.

1. The Axman of New Orleans - around 1918-1919

This notorious serial killer's weapon of choice was, you guessed it, an ax, where the murderer would slash victims' throats and brutally bash their heads in. The Axman normally attacked people at night while they were in their homes, always disappearing without a single trace of evidence or hint of his identity. The motives for the Axman's numerous killings remain unknown, but one thing remained consistent: he would use the axes he found in his victims' homes. Why the people of New Orleans wouldn't all just get rid of their axes is beyond me, but I'm sure we can all identify with the "oh no, that won't happen to me" mentality. The Axman left two letters in his time as an active serial killer. One extremely disturbing note read, "I shall leave no clue except my bloody axe, besmeared with blood and brains of he whom I have sent below to keep me company." He released another in following months stating, "I am very fond of jazz music, and I swear by all the devils in the nether regions that every person shall be spared in whose home a jazz band is in full swing at the time I have just mentioned." Peculiar, I know. New Orleans naturally responded by playing jazz music all throughout the streets on the night the letter was received. There were no victims that night, and the Axman claimed only one more victim afterwards. Many of The Axman's victims were Italian-American, which leads some to speculate that the mafia may have been involved. However, there is not nearly enough evidence to prove or disprove this theory.

2. The Zodiac Killer - late 1960s, early 1970s

Contrary to popular belief, this infamous serial killer is not Ted Cruz. He wasn't even alive during the start of these killings, which began around 1968 (Cruz was born in 1970). The Zodiac Killer, as he referred to himself, committed his crimes in Northern California, where 5 people were reported to have been killed, but he claimed to have killed 37 in his total "career." The Zodiac had multiple victims in a remarkably short period of time, and most near the same relative area. These reported incidents include the shooting of a couple in a parked car (twice), the shooting of a taxi driver, and a torturous shooting of two at a park. Although he wore an executioner-style hood with the Zodiac symbol on his chest, one of the park victims survived and was able to make out his face, identifying him as heavy set man with dark hair. Witnesses of the taxi driver murder identified the man as a stocky but skinnier white male with reddish-brown hair, and this time the man wore thick-rimmed glasses. The conflicting images of the man caused a variety of subjects to come into question, most notably, Earl Van Best Jr., Arthur Leigh Allen, and Lawrence "Kane" Kaye. All of these subjects have extremely incriminating evidence against them, yet just enough evidence in support of their innocence to exonerate any of them of being charged guilty. The most notable part of this narrative is the multitude of letters he left for the police and press, which he always marked with his signature Zodiac symbol. These mystifying letters included messages written in code. Only one of the cryptograms has since been solved. The killer admitted to all of his murders in his letters in great detail, but it was not enough to catch him. Even with a saliva sample from a stamp he had licked, the police could never pull any conclusive evidence.

3. The Murder of JonBenet Ramsey - December 1996

A normal December night turned into one of nightmarish panic for the Ramsey family when they found a ransom note on their back steps, and realized their 6 year old pageant queen was missing. The ransom note required $118,000, an oddly specific number, to be paid in order for their daughter to avoid being brutally murdered. The family called the police and neighbors, who helped look until she was found in their basement by her father, John Ramsey. She had been bludgeoned and strangled to death. Upon finding JonBenet, the first grave mistake took place. John immediately picked up his daughter's dead body, which had shown she had clearly been dead for a long time, and brought her upstairs. He had tampered with the crime scene. When we review previous pieces of evidence, the murder becomes intensely creepy, suggesting the killer(s) and those complicit may have had a closer connection to JonBenet and the Ramsey family than previously assumed. First, there were no signs of breaking and entering into the Ramsey household, and the ability of the killer to find JonBenet's room without waking anyone indicates a familiarity of the household. The killer also used a nylon cord and paintbrush that belonged to Patsy. Furthermore, the ransom note was written on Patsy Ramsey's notepad and with her pen. There was also a practice note that was found in the pad. There are also spelling and grammatical errors that seem deliberate, because easy words are misspelled while more complex words are spelled with apparent ease. This indicates that whoever wrote the letter may have been attempting to sound less educated than they actually were. The amount requested in the note was also almost the exact amount of money John had received for a bonus that year. Now, I'm not saying it was anyone in the family but...

4. The Black Dahlia - January 15, 1947

Dubbed Hollywood's most famous murder case, actress and homicide victim Elizabeth Short is far from receiving any form of justice. In a horrendous display of utter gore and mutilation, Short's disfigured corpse was found on Norton Avenue in Los Angeles. Her naked body had been cut completely in half at the torso and was completely drained of blood. To top it off, 3-inch gashes were cut into each corner of her mouth, creating the terrifying illusion of a bloody smile. After the case went viral and the search for the killer began in full force, many confessed. It was likely, however, that these confessors were merely desperate for publicity, because no evidence led back to any of them being an even probable suspect. The precision needed for the killer to slice the body clean in half and entirely drain her of blood had to be the work of someone markedly knowledgeable in human anatomy. Her killer had also left multiple letters, where he cut clippings from magazines as to not provide the police his handwriting. The letters were vague and eerily cryptic, thus not giving any indication as to who the murderer may have been. It was in these letters where he coined her new nickname, the "Black Dahlia", a name which the press perpetuated further. To this day, there is absolutely no clue as to who committed the gruesome murder of the the Black Dahlia.

5. Jack the Ripper - 1888-1891

Jack the Ripper, or so he called himself, is one of the most notoriously known serial killers of all time. He terrorized the Whitechapel district of London for years, remaining elusive and completely anonymous all the while. The time in which Jack the Ripper operated causes much to be left to the unknown. Without any form of substantial DNA test or modern forensics, the Ripper had very little trouble keeping his identity under wraps. To this day, there is still only minimal amounts of information available. The Ripper killed women, mostly prostitutes, who are still primarily unidentified. He mutilated and dismembered their bodies with a level of precision which, like the Black Dahlia's killer, suggests an above-average understanding of human anatomy. The five killings we can attribute to Jack occurred within a mile of each other. He allegedly taunted officers with letters, which may or may not have been authentic. Regardless, nothing revealed any identity or motive. Since 1888, hundreds of subjects have been named, including Queen Victoria's grandson, but of course, none have been found guilty.