20 Killer Words Every True Crime Buff Should Know

iStock.com/PaulFleet
iStock.com/PaulFleet

Whether we're preparing ourselves for the worst or we just love a good mystery, many of us can't get enough true crime content. True crime intersects with different fields like law, medicine, and forensics—all of which have their own vocabularies that can be hard for people on the outside to decode. Before binging The Staircase or Making a Murderer, brush up on these important terms every true crime fan should be familiar with.

1. COLD CASE

In legalese, a cold case describes a crime that remains unsolved, but isn't being actively investigated due to lack of evidence. The murder of JonBenét Ramsey, the D.B. Cooper hijacking, and the Jack the Ripper killings are all famous examples of cold cases.

2. LATENT PRINT

Crime scene investigator dusting door for prints.
iStock.com/zoka74

A latent print is a fingerprint made of the sweat and oil from one's skin (rather than blood or something more visible). Crime scene investigators usually need powders or chemicals to identify this type of print.

3. BLOOD SPATTER

Blood spatter is the pattern of bloodstains left at a violent crime scene. It's such important evidence in murder cases that there's an entire area of forensics dedicated to studying it. In theory, by analyzing the pattern of blood stains in a crime scene, the investigator can determine important details about the crime committed. But in recent years blood spatter analysis has been criticized. A 2009 report declared that it can give useful information about certain aspects of a crime, but that “the uncertainties associated with bloodstain pattern analysis are enormous” and that “the opinions of bloodstain pattern analysts are more subjective than scientific.”

4. PETECHIAL HEMORRHAGING

Cause of death isn't always obvious in murder cases. When looking at a potential strangulation victim, investigators examine their eyes for petechial hemorrhaging, or the tiny red dots that appear as a result of bleeding beneath the skin. Petechial hemorrhaging isn't a sure sign that someone has been choked to death, but it is likely to appear when the blood vessels in someone's head have been subjected to severe pressure.

5. MASK OF SANITY

Ted Bundy, Charles Manson, John Wayne Gacy—these serial killers were famous not only for their crimes, but their deceptively charming dispositions. This is what crime experts refer to as the Mask of Sanity. Coined by psychiatrist Hervey M. Cleckley in his 1941 book, this describes the phenomena of psychopaths easily blending in with their peers because they don't typically suffer from more noticeable mental symptoms like hallucinations and delusions.

6. MACDONALD TRIAD

The phrase Macdonald Triad first appeared in a paper by J. M. Macdonald published in a 1963 issue of the American Journal of Psychiatry. It refers to the three behaviors that, if exhibited in childhood, may indicate one's tendencies toward violence later in life. Those behaviors are animal cruelty, fire-starting, and chronic bed-wetting. While many prominent murderers have checked these boxes, experts today are skeptical of using this as a metric to identify future serial killers.

7. RIGOR MORTIS

Rigor mortis occurs when a body stiffens up a few hours after death as a result of calcium build-up in the joints and muscles. This can last a few days, and is one of the clues crime scene investigators use to determine when a murder took place.

8. ANGEL OF DEATH

"Angel of death" is the name given to medical professionals who intentionally kill their patients. In some cases the killer has convinced themselves they're helping the victim by choosing to end their life, which is why they're sometimes called "angels of mercy."

9. BLACK WIDOW

Female murderers are rare—they comprise just 15 percent of serial killers—but not unheard of. Women who commit murder are sometimes dubbed Black Widows after the spiders that devour their own mates after copulating. The moniker is usually reserved for a woman who targets people close to her, kills for personal gain, or uses her femininity to her advantage when committing the crime.

10. LUMINOL

Luminol reacting in glass.
deradrian, Flickr // CC BY-SA 2.0

Luminol is a chemical that emits a blue glow when mixed with a certain oxidizing agent. One of the substances that triggers this reaction is hemoglobin, the oxygen-carrying protein found in red blood cells. By spraying a violent crime scene with luminol, investigators can detect traces of blood that aren't visible to the naked eye.

11. GLASGOW SMILE

The Black Dahlia murderer mutilated Elizabeth Short before leaving her remains in a Los Angeles park in 1947. The wounds that would come to symbolize the case were two cuts connecting her ears to the corners of her mouth, giving her the appearance of a perpetual grin. Dubbed a Glasgow Smile because of its prevalent use among Scottish gangs in the 1920s and '30s, this mark has appeared in numerous murder cases since.

12. GUNSHOT RESIDUE

Gunshot residue (GSR) is made up of the propellant particles that are discharged during a gunshot. It often settles on the clothing of anyone who was within a few feet of a fired gun, and it can be an essential piece of evidence when connecting suspects to a crime.

13. BRAIN FINGERPRINTING

Recently featured in season 2 of Making a Murderer, brain fingerprinting is a relatively new practice in crime investigations. After a suspect is hooked up to a helmet that senses brain activity, they're given details about the alleged crime that only the perpetrator would know. If they recognize what's being described, the sensor is supposed to pick up the telltale electrical signals in their brain. While what research there is suggests that the technology may be more reliable than a polygraph test, there still haven't been enough studies to prove its validity.

14. JOHN/JANE DOE

In the world of crime, John or Jane Doe are the names given to a murder victim whose identity is being concealed from the public. These names are often used as placeholders in court cases.

15. MÜNCHAUSEN SYNDROME BY PROXY

Like Münchausen syndrome, people with Münchausen syndrome by proxy manufacture trauma to gain sympathy—but instead of harming themselves they choose people who are close to them as their victims. People with this condition might intentionally make their children sick or disabled, which sometimes leads to their death.

16. COPYCAT CRIME

A copycat crime occurs when the perpetrator is inspired by a different crime, whether it was depicted in a book, movie, or TV show or it happened in real-life. Investigators sometimes have trouble distinguishing between copycat killings and the acts of a single serial murderer.

17. TROPHY

Many serial killers collect "trophies" from their victims after committing a crime. These can be fairly innocuous, like jewelry and footwear, or as gruesome as body parts. Ed Gein—the real-life inspiration for the novel and movie Psycho—used the human souvenirs he kept from his murders to make clothing and furniture.

18. BALLISTICS

Gun at crime scene.
iStock.com/FireAtDusk

Ballistics is the study of the mechanics of firearms. In forensics, this science can help investigators identify gun deaths and determine where and how the weapon was used in a crime—and possibly who pulled the trigger. Though, in the past few years, the ability of ballistics to provide a definite answer has been called into question, with courts preferring "more likely than not" statements.

19. FORENSIC ENTOMOLOGY

One of the more unusual careers for someone who studies bugs is that of a forensic entomologist. These scientists look at how insects interact with crime scenes. Based on what type of bugs are hanging around a corpse and which stage of development they're in, a forensic entomologist can help investigators determine a time of death.

20. LOCARD'S EXCHANGE PRINCIPLE

Put simply, Locard's exchange principle is "with contact between two items, there will be an exchange." Twentieth-century forensic scientist Dr. Edmond Locard came up with this idea after observing that criminals will almost always bring something into the crime scene with them and leave something behind, providing valuable evidence to investigators.

Keep Your Cat Busy With a Board Game That Doubles as a Scratch Pad

Cheerble
Cheerble

No matter how much you love playing with your cat, waving a feather toy in front of its face can get monotonous after a while (for the both of you). To shake up playtime, the Cheerble three-in-one board game looks to provide your feline housemate with hours of hands-free entertainment.

Cheerble's board game, which is currently raising money on Kickstarter, is designed to keep even the most restless cats stimulated. The first component of the game is the electronic Cheerble ball, which rolls on its own when your cat touches it with their paw or nose—no remote control required. And on days when your cat is especially energetic, you can adjust the ball's settings to roll and bounce in a way that matches their stamina.

Cheerable cat toy on Kickstarter.
Cheerble

The Cheerble balls are meant to pair with the Cheerble game board, which consists of a box that has plenty of room for balls to roll around. The board is also covered on one side with a platform that has holes big enough for your cat to fit their paws through, so they can hunt the balls like a game of Whack-a-Mole. And if your cat ever loses interest in chasing the ball, the board also includes a built-in scratch pad and fluffy wand toy to slap around. A simplified version of the board game includes the scratch pad without the wand or hole maze, so you can tailor your purchase for your cat's interests.

Cheerble cat board game.
Cheerble

Since launching its campaign on Kickstarter on April 23, Cheerble has raised over $128,000, already blowing past its initial goal of $6416. You can back the Kickstarter today to claim a Cheerble product, with $32 getting you a ball and $58 getting you the board game. You can make your pledge here, with shipping estimated for July 2020.

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

“Slick” Julia Lyons: The Con Artist Who Posed as a Nurse During the 1918 Flu Pandemic—Then Robbed Her Patients

An actual nurse tends to a patient during the 1918 influenza pandemic.
An actual nurse tends to a patient during the 1918 influenza pandemic.
Harris & Ewing, Library of Congress, Wikimedia Commons // Public Domain

In September 1918, a 23-year-old woman “of marvelous gowns and haughty mien” was arrested at Chicago’s La Salle Hotel after a crime spree that included posing as a Department of Justice representative, cashing stolen checks, and performing “various miracles at getting ready money,” according to a Chicago Tribune article.

The authorities underestimated their slippery prisoner, who escaped from the South Clark Street police station before answering for her alleged offenses. By no means, however, had her brush with the law scared her straight. Soon after her police station disappearing act, Julia Lyons—also known as Marie Walker, Ruth Hicks, Mrs. H. J. Behrens, and a range of other aliases—concocted an even more devious scheme.

The Rose-Lipped, Pearly-Toothed Price Gouger

As The Washington Post reports, Chicago was in the throes of the 1918 influenza pandemic that fall, and hospitals were enlisting nurses to tend to patients at home. Lyons, correctly assuming that healthcare officials wouldn’t be vetting volunteers very thoroughly, registered as a nurse under several pseudonyms and spent the next two months caring for a string of ailing men and women across the city.

Lyons’s modus operandi was simple: After getting a prescription filled, she’d charge her patient much more than the actual cost. Once, she claimed $63 for a dose of oxygen that had actually cost $5 (which, once adjusted for inflation, is the same as charging $1077 for an $85 item today). Sometimes, “Flu Julia,” as the Chicago Tribune nicknamed her, even summoned a so-called doctor—later identified by the police as a “dope seller and narcotic supplier”—to forge the prescriptions for her. Then she’d flee the property, absconding with cash, jewelry, clothing, and any other valuables she could find lying around the house.

As for the physical well-being of her flu-ridden victims, Lyons could not have cared less. When 9-year-old Eddie Rogan fetched her to help his older brother George, who was “out of his head with illness,” Lyons retorted, “Oh, let him rave. He’s used to raving.” Unsurprisingly, George died.

Though pitiless at times, Lyons flashed her “rose-lipped smile and pearly teeth” and fabricated charming stories to gain the confidence of her clueless patients. To win over “old Father Shelhauer,” for example, she asked, “Don’t you remember me? Why, when I was a little girl I used to hitch on your wagons!” Shelhauer believed her, and threw a snooping detective off the scent by vouching for Lyons, whom he said he had known since she was a little girl.

Clever as she was, Lyons couldn’t evade capture forever. In November 1918, detectives eventually linked her to Eva Jacobs, another “girl of the shady world,” and wiretapped the home of “Suicide Bess” Davis, where Jacobs was staying. Through their eavesdropping, they discovered Lyons’s plans to marry a restaurant owner named Charlie. They trailed Charlie, who unwittingly led them straight to his new—and felonious—bride.

“The wedding’s all bust up! You got me!,” Lyons shouted as the detectives surrounded her. They carted the couple back to the station, where they asked a bewildered Charlie how long he had known Lyons. “Ten days!” he said. “That is, I thought I knew her.”

When it came time for Lyons to appear in court, Deputy Sheriff John Hickey volunteered to transport her.

“Be careful, she’s pretty slick,” Chief Bailiff John C. Ryan told him. “Don’t let her get away.” Detectives Frank Smith and Robert Jacobs, who had headed the investigation and arrested Lyons in the first place, echoed the sentiment, citing Lyons’s previous escape from South Clark Street.

“She’ll go if she gets a chance. Better put the irons on,” Jacobs advised. Hickey shook off their warnings with a casual “Oh, she won’t get away from me.”

He was wrong.

“Slick Julia” Escapes Again

Hickey did successfully deposit Lyons at the courthouse, where about 50 victims testified against her. An hour and a half after Hickey left with Lyons to bring her back to jail, however, the police received a phone call from an “excited” Hickey with some shocking news: Lyons had leapt from the moving vehicle and climbed into a getaway car—which sped away so quickly that Hickey had no hopes of chasing it down.

Hickey’s story seemed fishy. For one, he mentioned that they had stopped at a bank so Lyons could withdraw some cash, leading officials to believe that Hickey may have accepted a bribe to set her free. They also happened to be suspiciously far from their intended destination.

“If they were way out there,” Ryan told the Chicago Tribune, “They must have been cabareting together.”

Furthermore, a friend of Lyons named Pearl Auldridge actually confessed to the police that the entire plot had been prearranged with Hickey. He was suspended, and investigators were forced to resume their hunt for “Slick Julia.”

A Schemer 'Til the End

In March 1919, after poring through nurses’ registries for a possible lead, detectives finally located Lyons, under the name Mrs. James, at a house on Fullerton Boulevard, where she was caring for a Mrs. White.

“Mrs. M.S. James, née Flu Julia, née Slicker Julia, who walked away one November day from former Deputy Sheriff John Hickey, walked back into custody, involuntarily, last night,” the Chicago Tribune wrote on March 21, 1919.

In addition to her 19 previous counts of larceny, “obtaining money by false pretenses,” and “conducting a confidence game,” Lyons racked up a new charge: bigamy. Her marriage to Charlie the restaurateur still existed on paper, and Lyons had taken a new husband, a soldier named E.M. James, whom she had known for four days.

With no unscrupulous officer around to help Lyons escape yet again, she was left to the mercy of the court system. True to her sobriquet, “Slick Julia” stayed scheming until the very end of her trial, first claiming that she had been forced into committing crimes against her will by a “band of thieves,” and then pleading insanity. Nobody was convinced; the jury found Lyons guilty of larceny and the judge sentenced her to serve one to 10 years in a penitentiary.

Just like that, “Flu Julia” traded in her nurse's uniform for a prison uniform—though whether she donned her healthcare costume again after her release remains a mystery.