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

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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

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

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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.

10 Killer Gifts for True Crime Fans

Ulysses Press/Little A
Ulysses Press/Little A

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Humans have a strange and lasting fascination with the dark and macabre. We’re hooked on stories about crime and murder, and if you know one of those obsessives who eagerly binges every true crime documentary and podcast that crosses their path, you’re in luck—we’ve compiled a list of gifts that will appeal to any murder mystery lover.

1. Donner Dinner Party: A Rowdy Game of Frontier Cannibalism!; $15

Chronicle Books/Amazon

The infamous story of the Donner party gets a new twist in this social deduction party game that challenges players to survive and eliminate the cannibals hiding within their group of friends. It’s “lots of fun accusing your friends of eating human flesh and poisoning your food,” one reviewer says.

Buy it: Amazon

2. A Year of True Crime Page-a-Day Calendar; $16

Workman Calendars/Amazon

With this page-a-day calendar, every morning is an opportunity to build your loved one's true crime chops. Feed their morbid curiosity by reading about unsolved cases and horrifying killers while testing their knowledge with the occasional quizzes sprinkled throughout the 313-page calendar (weekends are combined onto one page).

Buy it: Amazon

3. Bloody America: The Serial Killers Coloring Book; $10

Kolme Korkeudet Oy/Amazon

Some people use coloring books to relax, while others use them to dive into the grisly murders of American serial killers. Just make sure to also gift some red colored pencils before you wrap this up for your bestie.

Buy it: Amazon

4. The Serial Killer Cookbook: True Crime Trivia and Disturbingly Delicious Last Meals from Death Row's Most Infamous Killers and Murderers; $15

Ulysses Press/Amazon

This macabre cookbook contains recipes for the last meals of some of the world’s most famous serial killers, including Ted Bundy, Aileen Wuornos, and John Wayne Gacy. This cookbook covers everything from breakfast (seared steak with eggs and toast, courtesy of Ted Bundy) to dessert (chocolate cake, the last request of Bobby Wayne Woods). Each recipe includes a short description of the killer who requested the meal.

Buy it: Amazon

5. Ripped from the Headlines!: The Shocking True Stories Behind the Movies’ Most Memorable Crimes; $15

Little A/Amazon

In this book, true crime historian Harold Schechter sorts out the truth and fiction that inspired some of Hollywood’s best-known murder movies—including Psycho (1960), Scream (1996), Arsenic and Old Lace (1944), and The Hills Have Eyes (1977). As Schechter makes clear, sometimes reality is even a little more sick and twisted than the movies show.

Buy it: Amazon

6. The Deadbolt Mystery Society Monthly Box; $22/month

CrateJoy

Give the murder mystery lover in your life the opportunity to solve a brand-new case every single month. Each box includes the documents and files for a standalone mystery story that can be solved alone or with up to three friends. To crack the case, you’ll also need a laptop, tablet, or smartphone connected to the internet—each mystery includes interactive content that requires scanning QR codes or watching videos.

Buy it: Cratejoy

7. In Cold Blood; $10

Vintage/Amazon

Truman Capote’s 1965 classic about the murder of a Kansas family is considered by many to be the first true-crime nonfiction novel ever published. Capote’s book—still compulsively readable despite being written more than 50 years ago—follows the mysterious case from beginning to end, helping readers understand the perspectives of the victims, investigators, and suspects in equal time.

Buy it: Amazon

8. Stay Sexy & Don’t Get Murdered: The Definitive How-To Guide; $13

Forge Books/Amazon

Any avid true crime fan has at least heard of My Favorite Murder, the popular podcast that premiered in 2016. This book is a combination of practical wisdom, true crime tales, and personal stories from the podcast’s comedic hosts. Reviewers say it’s “poignant” and “worth every penny.”

Buy it: Amazon

9. I Like to Party Mug; $12

LookHUMAN/Amazon

This cheeky coffee mug says it all. Plus, it’s both dishwasher- and microwave-safe, making it a sturdy gift for the true crime lover in your life.

Buy it: Amazon

10. Latent Fingerprint Kit; $60

Crime Scene Store/Amazon

Try your hand (get it?!) at being an amateur detective with this kit that lets you collect fingerprints left on most surfaces. It may not be glamorous, but it could help you solve the mystery of who put that practically empty carton back in the refrigerator when it barely contained enough milk for a cup of coffee.

Buy it: Amazon

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New Online Art Exhibition Needs the Public’s Help to Track Down Lost Masterpieces by Van Gogh, Monet, and More

Vincent van Gogh's original Portrait of Dr. Gachet wasn't stolen, but it hasn't been seen in 30 years.
Vincent van Gogh's original Portrait of Dr. Gachet wasn't stolen, but it hasn't been seen in 30 years.
Vincent van Gogh, Wikimedia Commons // Public Domain

If you wanted to compare both versions of Vincent van Gogh’s Portrait of Dr. Gachet in person, you couldn’t. While the second one currently hangs in Paris’s Musée d'Orsay, the public hasn’t seen the original painting since 1990. In fact, nobody’s really sure where it is—after its owner Ryoei Saito died in 1996, the precious item passed from private collector to private collector, but the identity of its current owner is shrouded in mystery.

As Smithsonian Magazine reports, Portrait of Dr. Gachet (1890) is one of a dozen paintings in “Missing Masterpieces,” a digital exhibit of some of the world’s most famous lost artworks. It’s not the only Van Gogh in the collection. His 1884 painting The Parsonage Garden at Nuenen in Spring was snatched from the Netherlands’ Singer Laren museum earlier this year; and his 1888 painting The Painter on His Way to Work has been missing since World War II. Other works include View of Auvers-sur-Oise by Paul Cézanne, William Blake’s Last Judgement, and two bridge paintings by Claude Monet.

Paul Cézanne's View of Auvers-sur-Oise was stolen from the University of Oxford's art museum on New Year's Eve in 1999.Ashmolean Museum, Wikimedia Commons // Public Domain

The new online exhibit is a collaboration between Samsung and art crime expert Noah Charney, who founded The Association for Research into Crimes Against Art. It isn’t just a page where art enthusiasts can explore the stories behind the missing works—it’s also a way to encourage people to come forward with information that could lead to the recovery of the works themselves.

“From contradictory media reports to speculation in Reddit feeds—the clues are out there, but the volume of information can be overwhelming,” Charney said in a press release. “This is where technology and social media can help by bringing people together to assist the search. It’s not unheard of for an innocuous tip posted online to be the key that unlocks a case.”

The exhibition will be online through February 10, 2021, and citizen sleuths can email their tips to missingmasterpieces@artcrimeresearch.org.

[h/t Smithsonian Magazine]