What's the Difference Between a Killer's Signature and M.O.?

iStock/fergregory
iStock/fergregory

True crime shows, documentaries, and podcasts are everywhere these days, not to mention all the crime-focused movies and TV shows—like NBC's Law & Order: SVU, CBS's CSI: Crime Scene Investigation, and Netflix's Mindhunter. And you've probably heard terms like signature and M.O. being thrown around a lot without much explanation as to what they mean, or how they're different.

If you're confused about the difference between them, well, you’re not alone. As former FBI agent and behavioral analyst John Douglas notes in his book Mindhunter: Inside the FBI's Elite Serial Crime Unit (which the Netflix series is based on), "Both [signature and modus operandi] are extremely important concepts in criminal investigations analysis, and I have spent many hours on witness stands of courtrooms throughout the country trying to get judges and juries to understand the distinction between them."

Douglas, who was recently in New York to promote his new book, The Killer Across the Table: Unlocking the Secrets of Serial Killers and Predators with the FBI's Original Mindhunter, out now, helped break down the difference between signature and M.O. for us.

M.O. stands for Modus Operandi, and, according to Douglas, it's a learned, dynamic behavior. "When a criminal starts perpetrating crimes, if something doesn't go right, he's got to perfect the M.O.," he tells Mental Floss. "He's got to get it better and better." In other words, unless an offender executes the perfect crime his first time out, he'll continue to tweak his M.O. as he goes. The method of committing the crime is modified for success. That's why, Douglas says, "you shouldn't link cases together strictly by modus operandi. … You don't do that because those characteristics could fit people that have nothing to do with the case as well."

But what you can use to link crimes together is an offender's signature, a term that Douglas says he coined. "A signature is a ritual—something [that] is done that is not necessary to perpetrate that particular crime," he says. "The signature is the ritual that is unique to the offender, and that's what you're looking for."

To demonstrate what he means, Douglas uses sports as an example. "It's like a baseball batter [who], before a ball comes in, does rituals," like touching his hat or cleats. "Or shooting a basketball: bounce it three times, [do a certain move], take the shot. It's not necessary to get it in the hoop or hit the ball, but in his mind he's got to do it. He's got to do it this way."

In Mindhunter, Douglas acknowledges that "the differences between M.O. and signature can be subtle." To demonstrate just how subtle, he compares two robbery cases. Both robbers made their captive undress; one "posed them in sexual positions, and took photographs of them" while the other did not take photos.

The latter made his hostages undress "so the eyewitnesses would be so preoccupied and embarrassed that they wouldn't be looking at him and so couldn't make a positive ID later on," Douglas writes. That's an example of M.O. The former robber is an example of a signature, because it wasn't something the offender had to do to rob the bank—and actually put him at risk of being caught, because he was in the bank longer. "It was something he clearly felt a need to do," Douglas writes.

Because the signature is unique to the offender, Douglas says that you can use it in trials: "A case in Washington state, the subject was posing the victims after he killed [them]. And all that was allowed for me to testify to."

There's one challenge with signatures, though. "You can only see it when it starts showing up in repetitive crimes," Douglas says. "You can't look at a single case and say, 'Oh, this was the signature.' Say the victim is posed—that may end up being the signature, but you've got to compare it to something, later on."

As criminology professor Scott A. Bonn, Ph.D., points out in a post for Psychology Today, "While every crime has an M.O., not all crimes have a signature." Now, whether you're listening to a true crime podcast or watching an episode of Mindhunter, you'll know the difference.

Why Do People Toss Beads During Mardi Gras?

Kameleon007/iStock via Getty Images
Kameleon007/iStock via Getty Images

Each year, more than 1 million people descend on New Orleans for Mardi Gras, an organized parade of debauchery and alcohol-induced torpor that may be the closest thing modern civilization has to the excesses of ancient Rome. Saturating the scene on Bourbon Street are plastic beads, handed or tossed to partygoers as a kind of currency. Some bare their breasts or offer booze in exchange for the tokens; others catch them in the air and wear the layers around their necks. Roughly 25 million pounds of beads are in circulation annually, making them as much a part of the Fat Tuesday celebration as sugary cocktails and King Cake.

Traditions and rituals can be hard to pin down, but Mardi Gras historians believe the idea of distributing trinkets began in the 1870s or 1880s, several hundred years after French settlers introduced the celebration to Louisiana in the 1600s. Party organizers—known locally as krewes—handed out baubles and other shiny objects to revelers to help commemorate the occasion. Some of them threw chocolate-covered almonds. They were joined by more mischievous attendees, who threw dirt or flour on people in an effort to stir up a little bit of trouble.

Why beads? Tiny tokens that represent wealth, health, and other prosperity have been a part of human history for centuries. In Egypt, tokens were handed out in the hopes they would guarantee a happy afterlife; the abacus, or bead-based system of accounting, used trinkets to perform calculations; pagan pre-winter rituals had people throwing grains into fields hoping to appease gods that would nourish their crops.

Humans, argues archaeologist Laurie Wilkie, display "bead lust," or a penchant for shiny objects. It's one possible reason why Mardi Gras attracts so many people with their arms in the air, elated to receive a gift of cheap plastic.

Photo of a well-dressed bulldog celebrating Mardi Gras in New Orleans.
Mario Tama, Getty Images

The early beads were made of glass before more efficient production methods overseas led to an influx of plastic beads in the 1960s. Unlike some of the more organic predecessors, these beads have come under criticism for being a source of health problems and pollution. Made from petroleum, they often harbor lead that seeps into the soil and rubs off on hands. (One estimate puts the lead deposit after a Mardi Gras celebration at 4000 pounds.) In 2017, New Orleans paid $7 million in clean-up costs to remove discarded beads from drain basins. In 2018, they installed gutter guards to prevent the necklaces from getting into the system in the first place. Meanwhile, scientists have been working to create an even more eco-friendly version of the beads—like a biodegradable version made from microalgae.

Environmental hazards aside, the beads of Mardi Gras have become as much a holiday staple as Christmas stockings or Thanksgiving turkeys. But the passion and desperate need for them is only temporary; in 2018, 46 tons of the beads were removed from just five blocks of the main parade route on Charles Street. And no bacchanal should leave that much bad juju behind.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Why Are Shower Doors in Hotel Rooms Getting Smaller?

sl-f/iStock via Getty Images
sl-f/iStock via Getty Images

Shower doors are shrinking in posh hotels, and minimalism is to blame, Condé Nast Traveler reports.

In lieu of hanging shower curtains or providing full shower doors, many newer hotels are opting for glass panels that cover only half the length of the shower. That’s frustrating for many travelers, who complain the growing trend is inconvenient and leaves bathroom floors sopping wet and slippery after shower use.

According to Condé Nast Traveler, the half-door trend began in European hotels in the 1980s. “A lot of it comes down to people trying to design hotel rooms with limited space,” boutique hotel designer Tom Parker told the magazine. “It’s about the swing of the shower door, because it has to open outward for safety reasons, like [if] someone falls in the shower. You have to figure out where the door swing’s going to go, make sure it’s not [hitting] the main door. It’s just about clearances.” A smaller door also has the added benefit of making the space appear larger than it really is, according to the magazine.

The trend is also connected to the birth of minimalist “lifestyle hotels,” which cater to a younger, hipper clientele that gravitates toward sleek lines and modern design. Plus, half-size glass doors are easier to clean than shower curtains, which tend to trap bacteria and need to regularly be replaced, which can add up to significant additional costs for a hotel.

Theoretically, even half-door showers are designed to minimize water spillage. Designers try to level the floors in bathrooms so water doesn’t pool in random areas, and they place shower heads and knobs in areas that are more protected by glass paneling. And where design doesn’t work, hotels try to pick up the slack.

“Hotels tend to mitigate the risks by offering non-slip interior shower mats, cloth bath mats for stepping out of the shower, grab bars, [and] open showers or no-sill showers which avoid having to step up and over the ledge,” designer Douglas DeBoer, founder and CEO of Rebel Design Group, told Condé Nast Traveler.

But the half-door trend still has yet to gain much love from hotel guests. “The older generation much, much prefers having a shower door,” Parker told Condé Nast Traveler. “I’m like a 70-year-old man at heart anyway. I like [a shower door] if it’s in keeping with the style of the rest of the room.”

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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