Subtitles section Play video Print subtitles Jeffrey Dahmer. Ted Bundy. John Wayne Gacy. And of course, the mysterious Jack the Ripper. They're names that strike fear into the hearts of any true crime buff. These are the household names of serial killers, but they're not the whole story. It's estimated that in 1987 alone, there were almost two hundred serial killers operating in the United States - and you probably haven't heard of most of them. But that doesn't mean they were any less deadly than the more famous ones. Here are thirteen of the most terrifying serial killers you've never heard of. #13. Vickie Dawn Jackson Hospitals are places of healing, and one of the most important positions there is the nurse. While the doctors do the trickiest procedures, nurses are the ones who interact the most with patients. That gave Vickie Dawn Jackson, a nurse at a North Texas hospital, the opportunity she needed. She was known as a wallflower in town, a quiet woman who never attracted much attention. But at her hospital in 2001, there was a mysterious epidemic of cases where patients came down with mysterious respiratory ailments and died - despite sometimes being hospitalized for minor ailments. Up to twenty patients had died, and the hospital soon realized that Jackson had been the last person to see all of them. But what was killing them? The investigation soon revealed missing vials of mivacurium chloride, a drug that can paralyze the breathing reflex. Despite a syringe with traces of the drug being found in her house, and witnesses reporting that she referred to “taking care” of patients who were causing trouble, it took over a year for her to be arrested! While she could have faced the death penalty for the ten counts of murder she was charged with, she ultimately pled No Contest to the charges and is serving a life sentence. But her attorney is calling for a new trial… No one expected her to be a serial killer - but the same can't be said for the next killer. #12. Carl Panzram Born to East Prussian immigrants in Minnesota, Carl Pazram was trouble from the time he was young. He was a notorious bully, and was in court for being drunk and disorderly from as young as eleven years old in 1902! His parents sent him to a reform school, and he was treated horribly by the staff members - leading him to burn it down. He spent the next decade in and out of juvenile hall and eventually prison, getting into fights wherever he went - but he was just ramping up his campaign of violence. Under an alias, he joined a ship's crew, and he and a fellow sailor stole a boat and killed the inhabitants. While his partner in crime was arrested, Panzram had his key to the world. His reign of terror was only beginning. After robbing the William H. Taft Mansion in Connecticut, Panzram had enough money to go anywhere he wanted. He traveled the world, killing men and boys alike. He was particularly fond of luring drunken sailors away and killing them. While he was arrested a few times for minor crimes, they never tied him to his murders, and he went on to travel to Portugeuese Angola and kill people while working on an oil rig. It was 1928 when he was finally arrested back in America for a burglary and confessed to several murders. He was given a sentence of twenty-five years to life - and quickly turned it into a death sentence by murdering a foreman. As he awaited execution, Panzram penned an autobiography where he claimed to have murdered twenty-two people - although only proof of five was found. He went to the gallows in 1930, taunting the executioner before the final drop. The next killer had a distinctly more innocent personality - sometimes. #11. Harrison Graham Harrison Graham was a seemingly non-descript man living in Philadelphia in the 1980s. He had history of problems in school and showed signs of an intellectual disability, but had mostly lived a quiet life and worked in the construction industry. But by 1983, he was living in a notorious drug den and had begun dealing pills himself. He still had a reputation as a good neighbor, but there was just one problem - a foul smell coming from his apartment. His landlord tried to evict him, but Graham refused to let him in and fled out the fire escape. The police were called to break open the apartment. What they found was horrifying. Two recently-killed women's bodies were found within, as well as five skeletons of women who had been killed long ago. A massive manhunt was launched for Graham, and he was eventually convinced to turn himself in by his mother. There, he confessed to the killings, saying he strangled the women while on drugs, but it soon became clear he may not have been in his right mind. He was fixated on a Cookie Monster toy and seemed to switch between three personalities - “Frank”, a drug-addicted killer; “Junior”, a confused toddler; and “Marty” a friendly man eager to cooperate. While the judge rejected his insanity defense and he was convicted of all the murders, there were doubts about his competence. He was sentenced to death - but was required to serve out a life sentence first, meaning he would never be executed. In prison, he was a model inmate - and actually became an ordained minister. The next killer was discovered in an even more shocking fashion. #10. Bela Kiss The year was 1914, and World War I was sweeping across the European continent. Countless young men on both sides of the conflict were drafted into action, and one was the quiet Hungarian tinsmith Bela Kiss. Twice married and the father of two, Kiss was very interested in finding himself another woman. He had long-distance correspondences with women through newspapers, and claimed to offer his services as a fortune-teller. His neighbors thought him an odd man, particularly for his obsession with the large oil drums he used to hoard gasoline for the coming war. They had no idea how right they were. After Kiss was drafted, the Budapest police came to confiscate the drums of gasoline for use by soldiers. But the drums were giving off an odd smell, and when the soldiers opened them, they were horrified - each of the drums contained the body of a murdered woman. In total, twenty-four bodies were found, and suddenly Kiss became one of the most wanted men in Europe. A search of his house found that he had been collecting information about murder, and had been defrauding and killing women for years. The military police eventually tracked Kiss down to a Serbian hospital, but the savvy serial killer was one step ahead. He placed another soldier's body in his bed, escaped - and was never seen again. He wasn't the only serial killer to terrorize the European continent in the early 1900s. #9. Peter Kurten German Peter Kurten had one of the most common stories of serial killers - being raised in an abusive home himself. Kurten didn't take long to follow in his father's footsteps, enjoying torturing animals and attempting to drown a playmate at the age of five. He would later claim to have begun his killing spree at the age of nine, pushing a child off a raft and leaving him to drown. As an adult, he spent time in and out of prison for a series of petty crimes, and his crimes soon escalated. Unlike many serial killers, he didn't have a favorite weapon - he would use whatever was available, and police had no idea a serial killer was on the loose. But Kurten would soon gain the nickname “The Vampire of Dusseldorf”. Kurten would kill at least nine victims over his decades-long killing spree, but he was undone by a simple mistake. When a young woman named Maria Budlick escaped from him in the woods, she told of her close encounter with Kurten in a letter to a friend. When the letter, addressed incorrectly, was opened by a postal worker, she gave it to the police, who got enough information from Maria to finally arrest Kurten. While his attorneys attempted an insanity defense, the jury was horrified by his many crimes and sent him to the guillotine. His head is currently on display at Ripley's Believe It Or Not in Wisconsin. This next killer was about as unassuming as it gets. #8. Lydia Sherman Born in 1824, Lydia Sherman was an orphan raised by her uncle, and married her first husband at sixteen. But after he lost his job in 1864, Sherman wasted no time - she poisoned him with arsenic after taking out insurance money on him. She collected the payout - and then set her sights on more targets. Three of her young children “died tragically” of typhoid fever within the next year - except that the true cause of death was arsenic, once again, allowing her to collect the insurance money. In total, she would poison six of her own children, three husbands, and two stepchildren - but would go undetected until 1872, because who would suspect a widow? When she was eventually arrested and convicted of second-degree murder, she would even be able to escape and find work as a housekeeper to a rich widower. He would be soon to meet an unfortunate fate as well, but Sherman was eventually caught and returned to prison, dying less than a year later from cancer. The next killer was able to carefully abuse his position of authority. #7. Gerard Schaefer In Martin County, Florida in 1972, Gerard John Schaefer, Jr. was the law. A sheriff's deputy, he had been working patrol since he was twenty-five years old. But he had a sick obsession. From a young age, he had been fixated with spying on young women and killing animals. He was fired from a teaching job and rejected from the priesthood in quick succession before turning to law enforcement. That job would come to an end as well when he picked up two teenage hitchhikers and kidnapped them, tying them up in the woods. When they escaped and reported Schaefer, he claimed he had just been trying to teach them a lesson. He was fired, but it was only the beginning. Two months later, Schaefer would kidnap and murder two teenage girls, and similarities between that case and the hitchhikers who escaped led police to look into Schaefer. They searched his house and found disturbing stories full of descriptions of kidnapping and murdering women who he referred to as “whores”. While Schaefer was only convicted of the two murders and given a life sentence, he was suspected in the murders of up to thirty women and girls around the country - something he would boast about to anyone who would listen. But he would take those secrets to his grave when he was stabbed to death by a fellow inmate in 1995. This next killer led a campaign of terror across the great white north. #6. Robert William Pickton Robert Pickton was a pig farmer in a small town in British Columbia, and he had a dark past. He and his brother's farm was a run-down place that many people suspected was a front for criminal and gang activity, and in 1997 he was arrested for the attempted murder of a sex worker. But Bill Hiscox, a worker on the farm, noticed one thing he couldn't ignore - women who visited the farm kept going missing. After police obtained a warrant to search the farm for fireworks, they were able to get enough evidence to charge Pickton with six murders, for which he was sentenced to life in prison - but they eventually added charges for twenty murders. While he wasn't convicted of these new charges, he reportedly taunted authorities that he was only one short of fifty murders when he was caught. Pickton wound up being notable not just for being the most prolific serial killer in Canadian history, but for inadvertently bringing attention to the number of First Nations Canadian women who go missing each year. Our next killer was able to hide behind a pretty face - for a time. #5. The Co-Ed Killer It was 1967 when the area of Ann Arbor, Michigan was terrorized by a serial killer. Young women started turning up dead one by one after being stabbed, strangled, or mutilated. The first victim, Mary Flezar, would be found on an abandoned farm by two teenage boys, but it would be almost a year before the horror repeated itself. When the second victim was said to have been seen with college student John Norman Collins, the police questioned him - but the charming young man was soon let go for lack of evidence. Six more young women would be found dead, but when Collins' name came up again, the police zeroed in on him and searched his house. They found bloodstains, and Collins was charged with murder. The handsome all-american boy was revealed to have a dark obsession with bondage, torture, and murder - and it earned him life in prison, where he remains to this day. But the rest of these killers made a name for themselves in sheer numbers. #4. The Harpe Brothers Often considered America's first serial killers, Micajah and Wiley Harpe were terrorizing the American south almost as long as there was a United States. These two loyalists to the British crown had been on the wrong side of the war, and became notorious outlaws. Unlike many other serial killers, they didn't have a specific type of victim, and they didn't seem to be obsessed with killing itself. They committed robberies, they set fire to buildings, and they targeted women and men alike. It wouldn't be long before posses were organized across Appalachia to hunt for them. While they shared many traits with the Highwaymen of the times - often brutal robbers who targeted travelers - the Harpes seemed to be in it as much for the thrill as anything. They may have killed as many as fifty people before joining up with the notorious Mason Gang of river pirates. But when they killed the leader and tried to collect a bounty on him, they were recognized and arrested. And after a brief escape attempt, the violent rampage of the Harpe brothers ended at the gallows - their heads put on display as a warning to other outlaws. These next killers were among the most unlikely. #3. Los Poquianchis Rancho El Angel was a notorious hub of prostitution and other criminal activity in the Mexican state of Guanajuato. But it wasn't run by your everyday Cartel leader - it was run by the Gonzalez Valenzuela sisters, a quartet of the most ruthless women Mexico has ever seen. Maria Delfina, Maria Del Carmen, Maria Luisa, and Maria de Jesus got away with their crime spree for years until police picked up a woman named Josefina who had been working as a go-between for the sisters. She was suspected of kidnapping girls to be taken to Rancho El Angel, and she quickly spilled all. What she revealed shocked everyone. The sisters had made Rancho El Angel one of the worst sites of mass murder in Mexican history. The police raid found the bodies of almost a hundred people. The sisters had been killing prostitutes when they became too sick or old, forcing them to swallow drugs for transport,and murdering men who came there with lots of money on them. Their crimes exposed, the sisters finally faced trial. Delfina and Carmen died in prison, Maria Luisa went mad and was sent to an asylum, and Maria De Jesus completed her forty-year sentence and was released - with her whereabouts post-prison unknown. The next killer turned the last frontier into his personal killing grounds. #2. Robert Hansen Scarred by acne and shy due to a stutter, Robert Hansen didn't seem like the intimidating type. But his unassuming appearance hid a seething hatred for the women who ignored him. After serving a stint in the Army Reserve, Hansen moved to Alaska with his second wife and became deeply involved in hunting. He was arrested several times for assaults, thefts, and abductions, but it wasn't until 1972 that the horrors really started. Robert Hansen was about to go hunting for bigger game. He began targeting sex workers around Anchorage, kidnapping and torturing them. But he wasn't satisfied with simply killing them. He would release them and then proceed to hunt them like animals. Bodies were found around Anchorage, but no connection was found until one of his targets managed to get away. Cindy Paulson managed to escape before being taken to Hansen's isolated cabin, and described his truck enough to police that they were able to find him. Hansen was charged with seventeen murders, but is believed to have killed up to twenty-one. He was sentenced to 461 years plus life in prison, where he remained until his death in 2014. But for the most prolific killer of them all, you have to go to South America. #1. The Monster of the Andes Pedro Lopez grew up in Colombia, one of thirteen children, and displayed disturbing behavior from when he was young - reportedly abusing his siblings. By eighteen, he was a car thief, and did time in prison where he reported being horribly abused. He was released - but what came out of prison was something different and terrible. He would soon move to Peru and begin targeting young girls. He claimed to have killed over a hundred when he was captured by a local tribe. They planned to execute him, but a local missionary convinced them to hand him over to the police instead. The police released him - a terrible mistake. He would return to Colombia, and then to Ecuador, and continue his hunt until he was caught in 1980 while trying to abduct a girl by some market traders. When he was taken into custody, he confessed to killing over a hundred girls. While the police were dubious, they were about to get horrifying proof - a flash flood revealed a mass grave containing many of his victims. He was sentenced to prison for killing 110 girls, but was shockingly released in 1998.