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Are These Crime Drama Clues Fact or Fiction?

Steven Avery, featured in the Netflix documentary Making a Murderer, served 18 years in prison for rape, then was exonerated by DNA. He was convicted of murder in 2007, based partly on DNA evidence.
Steven Avery, featured in the Netflix documentary Making a Murderer, served 18 years in prison for rape before being exonerated by DNA in 2003. In 2007, he was convicted of murder, based partly on DNA evidence.

I’m often just as surprised by what forensic scientists can’t do as by what they can. In the Netflix documentary Making a Murderer, for instance, the question of whether police planted the main character’s blood at a crime scene comes down to whether or not the FBI can detect a common laboratory chemical called EDTA in a bloodstain.

On a TV crime show, this would be a snap. The test would take about five minutes and would involve inserting a swab into a magic detector box that beeps and spits out an analysis of every substance known to humankind.

In real life, there’s no common and accepted test in forensic labs for EDTA even today, nine years after the FBI tested blood for the Steven Avery trial featured in Making a Murderer. In that case, the FBI resurrected a test they had last used in the 1995 O.J. Simpson trial, and testified that the blood in question did not contain EDTA and therefore was not planted using EDTA-preserved blood from an evidence vial. (Avery was convicted.)

Questions about the test’s power and reliability have dogged the case ever since. There’s even an in-depth Reddit thread where fans of the Netflix show are trying to sort out the science.

Having worked in chemistry labs, it surprised me at first that this analysis would be difficult or controversial. After all, a quick search of the scientific literature turns up methods for detecting low levels of EDTA in everything from natural waters to beverages.

Steven Averys
Steven Avery’s attorneys Jerome Buting (shown) and Dean Strang struggled to dispute chemical evidence introduced mid-trial that undermined the idea that police had planted blood evidence.

But the key here is that we’re talking about forensic science, not beverage chemistry. Beverage chemistry, in this case, is much more exacting. Was there really no EDTA in the blood swabbed from victim Teresa Halbach’s vehicle, or was the chemical simply too diluted or degraded to be detected with the FBI’s method? Could the test have missed a small amount of EDTA? It would be hard to say without further experiments that replicate crime scene conditions, experiments that essentially put the test to the test.

The reality is that forensic science today is a strange mix of the high-tech and the outdated, so questions about evidence like those in Avery’s case are not uncommon. Methods that we take for granted, like measuring a particular chemical, or lifting a fingerprint off a gun and matching it to a suspect, can be difficult—and far from foolproof. On the other hand, some of the real science happening now sounds like something dreamed up by Hollywood script writers, such as new methods aiming to reconstruct what a person’s face looks like using only their DNA.

Making a Murderer, whether it sways your opinion on Steven Avery or not, has done a service by getting people interested in something as arcane as EDTA tests, and by showing why real-life crimes are not solved nearly so neatly as fictional ones.

I see the messiness of forensic science all the time, because I scan its journals and often come across new studies that make me think either “you mean we couldn’t already do that?” or “I had no idea that was possible.” I’ve gathered a few recent examples for a quiz.

How well can you separate CSI fact from fiction? Here are a few crime-solving scenarios I’ve cooked up; see if you can tell which use real methods based on new forensic research. You’ll find the answers below.

  1. A skeleton is found buried in a shallow grave. The body’s soft tissues have completely decomposed, so only the teeth and bones remain. A forensic anthropologist examines the bones and reports that they come from a female who was five foot six inches tall, and obese. Could she really tell the person was overweight?
  2. The body of a white male in his 50s turns up on a nature trail, scavenged by animals. The victim’s bones show a number of puncture wounds consistent with animal bites, but x-rays reveal fine lines of different density in the bone around some of the punctures. An expert says these lines show that the wounds were made about 10 years before death. Is it possible to tell the approximate age of these wounds from x-rays?
  3. A woman is found dead in her home, bludgeoned to death. A bloody frying pan lies on the floor next to her. Her husband is the main suspect. Fingerprints on the pan’s handle are too smudged to make a definitive ID, but an analyst says she can still rule out the husband: All of the fingerprints on the pan came from a woman, the expert says. Is it possible to tell if the fingerprints were from a male or female?
  4. A woman is sexually assaulted and identifies her male attacker in a lineup. The suspect’s DNA matches DNA found on her body. It looks like an easy case for the prosecutor—until the suspect reveals that he has an identical twin. Neither twin admits to the crime. Is it possible to tell which twin’s DNA was found at the crime scene?
  5. A witness sees a man in a stocking mask rob and shoot a man outside his home. A stocking is found near the house, and a hair-analysis expert testifies that 13 hairs in the mask are all human head hairs from an African-American. A microscopic analysis matches the characteristics of one hair to a particular African-American suspect. The prosecutor tells the jury that the chances are one in ten million that this could be someone else’s hair. Can hairs be matched to an individual this accurately?


Answers Below


  1. Yes. Biologists have long known that greater body mass changes the weight-bearing bones of the legs and spine, and a new study shows that even bones that aren’t supporting most of the body’s weight, such as arm bones, have greater bone mass and are stronger in obese people. So even in a skeleton missing its legs, our forensic anthropologist might be able to tell that the person was obese.
  2. No. This one is from an actual episode of Bones (The Secret in the Siege, Season 8, Episode 24, reviewed here by real-life bioarchaeologist Kristina Killgrove). In the episode, Dr. Temperance Brennan uses Harris lines to determine the age of bone injuries in two victims. Harris lines are real, but they form only in growing bones, so are useful only in determining childhood injuries or illness.
  3. Yes. A study published in November showed that the level of amino acids in sweat is about twice as high in women’s fingerprints as in men’s. Of course, as with all the new methods, this one could face challenges as evidence in a U.S. court of law, where the Daubert standard allows judges to decide whether scientific evidence is admissible based on factors including its degree of acceptance by the scientific community.
  4. Yes, if you do it right. Standard DNA tests don’t distinguish between twins, who are born with nearly identical DNA, but it’s possible to do a more sophisticated test to catch post-birth mutations and epigenetic differences, which you can think of as genetic “add-ons” that don’t affect the DNA sequence itself. One new test distinguishes between twins by looking for small differences in the melting temperature of their DNA that are caused by such epigenetic modifications.
  5. No. The field of hair analysis has come under heavy scrutiny, especially after a review by the U.S. Justice Department revealed major flaws in 257 out of 268 hair analyses from the FBI. The case described here is the real-life case of Santae Tribble, convicted in 1978 of murder. In 2012, DNA tests showed that none of the hairs matched Tribble—and one was from a dog.

9 thoughts on “Are These Crime Drama Clues Fact or Fiction?

  1. And the cops that planted evidence will never be looked for or found. Even if they are found, they would never get punished. That is the true nature of our police force. Personally, I think we would all be safer, and have much less crime, if we just got rid of cops completely. Most are too incompetent to actually conduct a real investigation, and almost all are far too corrupt and lazy to try. Case in point: I can walk by any crack house and be able to identify it as such. This is not due to my brilliance, but just to my street smarts. Yet, a cop will never go near it. Why? Generally, they are either afraid to go near it, or they are paid to stay away from it. I could go on and on and on, but that story just gets so old. In short, Emma Goldman was right. Cops are there to make sure stolen property remains stolen. In other words, they are there to step on poor people and keep them afraid so the rich can keep on stealing from everyone.

    1. Really Jim? Whilst yes it’s easy to say ‘street smarts’ allow you to figure where a crack house is, they’re not allowed to investigate without probably cause or they get reprimanded when they fuck up. Yeah cops can be last (and assholes) at times and probably don’t want to do the extra paperwork, it’s not as though all are morally corrupt people taking bribes everywhere.
      Ps: may be difficult when your position is general duties as apposed to being in small crime investigations.

      1. I guess we can see who lives in the fantasy world. I live in the real world. Cops are the most corrupt sector of our truly criminal justice system. Remember, while you might see some brutality on YouTube; I’ve lived it. Please pull your head out of your ass. Our entire system is screwed.

      2. I am retired and have never in my long life had to call the police to mediate anything. It is possible that Jim is correct, but the prospect of “flying without a parachute” and no policing is too terrifying for most to imagine. Most white people that is. I, too, while caucasian, have been on the receiving end of their absurd ideas of balance. I have nephews that because of their skin color have to alter their behavior because of a real fear of being killed. And now, with heroin becoming a white disease, even the drug laws – once horrific and unbelievable – are being modified toward treatment instead of incarceration. Remember the “crack” epidemic? See the difference? Either policing has to be beholden to a civil authority, with prosecutorial power or the current “us vs. them” blue wall will be the continuing and problematic standard.

  2. In a real world, them corrupt pigs shouldnt have been the ones investigating the murder case…leave that to the pros. Just cause Mr Avery was suing for 36 mil, they (corrupt pigs) had to make sure he went down, turning the conviction now would cause mayhem only for having to charge several corrupt pigs for murder and many other charges.

  3. I continue to have to scrape my chin off the ground with this one. Because I’m so shocked that this poor man is still in prison; even after all the outpouring of support for him. The producers of this documentary did an excellent job proving many points of shady investigating and unprofessional grudges and judgments against this poor man. They make it very clear that two of the sheriff’s in this town are carrying grudges for this man and have been for many years now. The problem is that this grudge has turned into a long and vicious pattern of corruption and deceit the likes of mob rule. Bravo to the police department and the judge for sticking together so well over the years without even one person caving in and spilling the beans about the truth of the collaborative mishandling of this man’s life and trail. The mob can learn a great deal from this police department about how to keep your mouth shut and how to keep your informants close so you can ruin as many lives by breaking the law as you possibly can.
    Here is the real reason this man will never get out of prison. If anyone says the evidence was not handled properly or someone lied or there was improper handling of witnesses; it calls into question every conviction over the last 20 years of which this judge was involved. It also calls into question every arrest made over the last 20 years by these sheriffs. It would be a financial and moral disaster for the entire state. It would bring forward an extent of corruption that would break records and call into question the entire checks and balances in our judicial system. No one wants to open that can of worms. They would rather allow a single man to rot in prison as a sacrifice, rather than bring down the whole house. The good of the many over the good of the few, or one in this case. He will die in prison before anyone tries to make things right by his family.

    1. If they put the guilty parties, who had wrongfully denied this man his freedom, in jail; then released every single person arrested or convicted by those criminals, the crime rate would be lower. Law enforcement is the mob. It is not similar, it is the same.

  4. Like history, who decides what it is to be? Discoveries now found continue to alter history are
    mind boggling. This, too, can apply to forensics. someone in power wants the outcome to meet his/her ‘truth’; yet, Mr Avery’s life is being destroyed because there may be someone who wants him to be guilty. Guilty people should account for their transgressions.

    Suggestion: Before any serious crime is adjudicated have the unknown suspect’s crime information submitted to an impartial diverse group to review the evidence with added mechanisms that can help prove guilt or not.

    THEN, put the ones who arrested and provided evidence and the forensic expert under a microscope before the trial–if there is to be one. This may be expensive but not as much as to be sued later because the person was later found innocent. More important the havoc this has played on this innocent person’s life is almost unforgivable.

    1. Or you could just take Machievelli’s approach and admit that government (the ruling authority of any justice system) has nothing to do with justice. 🙂

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