Double Trouble: When Identical Twins Run Into the Law

Last night, Law & Order: SVU did that “ripped from the headlines” thing where they borrow elements of real-world criminal cases or address current issues in law enforcement. The episode, “Double Strands,” revolved around a topic I've been reading a lot about lately: twins.

[Spoilers Ahead!]

The plot involves a serial rapist and his identical twin brother, who is falsely accused of the crimes. The SVU detectives eventually figured things out, but real-world police have had a lot of trouble with identical twins in several high-profile cases. DNA evidence — a tool that’s supposed to help convict the guilty and exonerate the innocent accurately and efficiently — has complicated cases where a twin or twins have been involved. This is because identical twins are the result of a single fertilized egg that formed one zygote, which then divided into two separate embryos. The siblings have nearly identical DNA, and we've yet to figure out how to discern one twin from the other using DNA analysis.

[End Spoilers]

The Headlines From Which The Story Was Ripped

One summer night in 2001, Darrin Fernandez attempted to break into an apartment in Boston’s Dorchester neighborhood. When he smashed a window to get inside, he not only alerted the person who lived in the apartment, but also cut himself deeply on the jagged glass. He fled, and police soon found him, still bleeding, as he tried to escape.

When the police analyzed DNA from the broken glass and from Fernandez, they found that he was a match for genetic material recovered in two unsolved sexual assaults cases, both of which were committed within a few blocks of the apartment Fernandez had tried to break into.

Fernandez was convicted of attempted breaking and entering at the apartment. He was also eventually convicted of one of the sexual assaults, for which there was plenty of evidence that implicated him, including the victim noticing a tattoo that his brother did not have (in the SVU episode, both twins have a similar tattoo in the same place). The police and prosecutors could not confidently put the second assault on him, though. The DNA match was the only substantive evidence that they had to go on, and it turns out that it also matched a second person: Fernandez’s identical twin brother, Damien.

There were no witnesses to the assault, no accomplices to roll, and no fingerprints at the scene. Darrin didn’t have an alibi to cover the time of the assault, but neither did Damien. The police couldn’t place either brother at the scene of the crime and the DNA that damned Darrin in another trial had only established reasonable doubt in this one. The case went to trial anyway and after four days of deliberation, there was a hung jury and a mistrial.  In a second trial several months later, the prosecution’s case rested heavily on the fact that Darrin worked as a painter near where the assault occurred, and he had the opportunity to case the neighborhood. Again, the jury was hung and a mistrial was declared.

In 2006 Fernandez went to trial a third time, and prosecutors were allowed to present for the first time evidence that he had committed four break-ins in the victim’s neighborhood within a year (and had been convicted of a similar sexual assault in one of those instances). The victim of that assault, who had not testified at the previous two trials, also took the stand this time around to highlight the similarities her attack shared with this case.

The jury returned a guilty verdict and, five years after his initial arrest, Darrin Fernandez was sentenced to 15 to 20 years on top of 10 to 15 year sentence he was already serving for the first assault.

Police and prosecutors in Grand Rapids, Michigan, may have had it even worse. In 1999, presented with DNA evidence in the rape of a college student, they couldn’t figure out which of their twin suspects to even charge with the crime.

Like the Fernandez cases, there were no witnesses and no fingerprints. To complicate matters, the suspects in this case, Tyrone and Jerome Cooper, both had records for sexual assault (Tyrone assaulted a 10-year-old girl in 1991 and Jerome a 12-year-old girl in 1998).

After hiring a biotechnology company to check some 100,000 DNA characteristics to match one twin or the other to the recovered evidence, the police came up empty. They could only tell both twins that the case would be not be forgotten and would get worked until the statute of limitations prevented prosecution.
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Twins make the justice system work even harder when they’re attached to each other, literally. If a conjoined twin commits, and is convicted of, a crime, how do you punish them without also unjustly punishing their innocent sibling? Slate’s Daniel Engber and legal scholar Nick Kam have both looked at the available historic cases and suggested possible solutions to the problem.

Anne Dirkse, Flickr // CC BY-SA 2.0
10 Astonishing Things You Should Know About the Milky Way
Anne Dirkse, Flickr // CC BY-SA 2.0
Anne Dirkse, Flickr // CC BY-SA 2.0

Our little star and the tiny planets that circle it are part of a galaxy called the Milky Way. Its name comes from the Greek galaxias kyklos ("milky circle") and Latin via lactea ("milky road"). Find a remote area in a national park, miles from the nearest street light, and you'll see exactly why the name makes sense and what all the fuss is about. Above is not a sky of black, but a luminous sea of whites, blues, greens, and tans. Here are a few things you might not know about our spiraling home in the universe.


The Milky Way galaxy is about 1,000,000,000,000,000,000 kilometers (about 621,371,000,000,000,000 miles) across. Even traveling at the speed of light, it would still take you well over 100,000 years to go from one end of the galaxy to the other. So it's big. Not quite as big as space itself, which is "vastly, hugely, mind-bogglingly big," as Douglas Adams wrote, but respectably large. And that's just one galaxy. Consider how many galaxies there are in the universe: One recent estimate says 2 trillion.


artist's illustration of the milky way galaxy and its center
An artist's concept of the Milky Way and the supermassive black hole Sagittarius A* at its core.
ESA–C. Carreau

The Milky Way is a barred spiral galaxy composed of an estimated 300 billion stars, along with dust, gas, and celestial phenomena such as nebulae, all of which orbits around a hub of sorts called the Galactic Center, with a supermassive black hole called Sagittarius A* (pronounced "A-star") at its core. The bar refers to the characteristic arrangement of stars at the interior of the galaxy, with interstellar gas essentially being channeled inward to feed an interstellar nursery. There are four spiral arms of the galaxy, with the Sun residing on the inner part of a minor arm called Orion. We're located in the boondocks of the Milky Way, but that is OK. There is definitely life here, but everywhere else is a question mark. For all we know, this might be the galactic Paris.


If you looked at all the spiral galaxies in the local volume of the universe, the Milky Way wouldn't stand out as being much different than any other. "As galaxies go, the Milky Way is pretty ordinary for its type," Steve Majewski, a professor of astronomy at the University of Virginia and the principal investigator on the Apache Point Observatory Galactic Evolution Experiment (APOGEE), tells Mental Floss. "It's got a pretty regular form. It's got its usual complement of star clusters around it. It's got a supermassive black hole in the center, which most galaxies seem to indicate they have. From that point of view, the Milky Way is a pretty run-of-the-mill spiral galaxy."


On the other hand, he tells Mental Floss, spiral galaxies in general tend to be larger than most other types of galaxies. "If you did a census of all the galaxies in the universe, the Milky Way would seem rather unusual because it is very big, our type being one of the biggest kinds of galaxies that there are in the universe." From a human perspective, the most important thing about the Milky Way is that it definitely managed to produce life. If they exist, the creatures in Andromeda, the galaxy next door (see #9), probably feel the same way about their own.


John McSporran, Flickr // CC BY 2.0

We have a very close-up view of the phenomena and forces at work in the Milky Way because we live inside of it, but that internal perspective places astronomers at a disadvantage when it comes to determining a galactic pattern. "We have a nice view of the Andromeda galaxy because we can see the whole thing laid out in front of us," says Majewski. "We don't have that opportunity in the Milky Way."

To figure out its structure, astronomers have to think like band members during a football halftime show. Though spectators in the stands can easily see the letters and shapes being made on the field by the marchers, the band can't see the shapes they are making. Rather, they can only work together in some coordinated way, moving to make these patterns and motions on the field. So it is with telescopes and stars.


Interstellar dust further stymies astronomers. "That dust blocks our light, our view of the more distant parts of the Milky Way," Majewski says. "There are areas of the galaxy that are relatively obscured from view because they are behind huge columns of dust that we can't see through in the optical wavelengths that our eyes work in." To ameliorate this problem, astronomers sometimes work in longer wavelengths such as radio or infrared, which lessen the effects of the dust.


Astronomers can make pretty reasonable estimates of the mass of the galaxy by the amount of light they can see. They can count the galaxy's stars and calculate how much those stars should weigh. They can account for all the dust in the galaxy and all of the gas. And when they tally the mass of everything they can see, they find that it is far short of what is needed to account for the gravity that causes the Milky Way to spin.

In short, our Sun is about two-thirds of the way from the center of the galaxy, and astronomers know that it goes around the galaxy at about 144 miles per second. "If you calculate it based on the amount of matter interior to the orbit of the Sun, how fast we should be going around, the number you should get is around 150 or 160 kilometers [93–99 miles] per second," says Majewski. "Further out, the stars are rotating even faster than they should if you just account for what we call luminous matter. Clearly there is some other substance in the Milky Way exerting a gravitational effect. We call it dark matter."


Dark matter is a big problem in galactic studies. "In the Milky Way, we study it by looking at the orbits of stars and star clusters and satellite galaxies, and then trying to figure out how much mass do we need interior to the orbit of that thing to get it moving at the speed that we can measure," Majewski says. "And so by doing this kind of analysis for objects at different radii across the galaxy, we actually have a fairly good idea of the distribution of the dark matter in the Milky Way—and yet we still have no idea what the dark matter is."


andromeda galaxy
The Andromeda galaxy
ESA/Hubble & NASA

Sometime in the next 4 or 5 billion years, the Milky Way and Andromeda galaxies will smash into each other. The two galaxies are about the same size and have about the same number of stars, but there is no cause for alarm. "Even though there are 300 billion stars in our galaxy and a comparable number, or maybe more, in Andromeda, when they collide together, not a single star is expected to hit another star. The space between stars is that vast," says Majewski.


There are countless spacecraft and telescopes studying the Milky Way. Most famous is the Hubble Space Telescope, while other space telescopes such as Chandra, Spitzer, and Kepler are also returning data to help astronomers unlock the mysteries of our swirling patch of stars. The next landmark telescope in development is NASA's James Webb Space Telescope. It should finally launch in 2019. Meanwhile, such ambitious projects as APOGEE are working out the structure and evolution of our spiral home by doing "galactic archaeology." APOGEE is a survey of the Milky Way using spectroscopy, measuring the chemical compositions of hundreds of thousands of stars across the galaxy in great detail. The properties of stars around us are fossil evidence of their formation, which, when combined with their ages, helps astronomers understand the timeline and evolution of the galaxy we call home. 

What Pop Culture Gets Wrong About Dissociative Identity Disorder

From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.


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