FORENSICS 116: CRIMSON CLUES by Robert C. Jones
Posters Note: Once again I find myself wishing I could take credit for this piece, but though it may show up under my name that fact is purely because Bob Jones is still having computer difficulty and asked me to post it for him. Posting automatically defaults to certain format conventions of the poster’s password. The research, brilliance and authorship, be assured, is entirely that of Robert C. Jones.
The very thoughts of blood spatters usually make one at least uncomfortable. Coupled as they are with thoughts of what happened or might have happened to cause the spatters, that is certainly a perfectly normal reaction. Forensic analysts, however, need to uncouple such thoughts as best they can to an extent that they can hear the myriad bits of information the splatters have to share with them.
Blood external to bodies has had information to impart for a long time, and we have been developing techniques to recognize and interpret that information. A century ago, scientists discovered that human blood could be divided into four types, namely, A, AB, B and O and that these types were genetically inherited. The types were identifed according to the presence or absence of antigens on red blood cells and the presence or absence of their antibodies in blood serum. This discovery enabled safer blood transfusions and also provided forensic advantages. Since large numbers of persons share the same blood type, blood typing cannot be used to positively identify a suspect as being the source of a particular blood stain; but it certainly can be used to exclude a suspect.
Blood typing also established a means for determining parental relationships. The method was far from perfect, however. The percentage of persons it would exclude from being the parent of a child was only about 30 percent. In fact, if a child’s blood was type A and its mother’s blood was type AB, based only on blood typing, any man in the world could potentially have been the child’s father. Science has advanced considerably, though. Today, using DNA analysis, paternity testing laboratories claim paternity test reliability as high as 99.99 percent.
An early step in analyzing blood stains at a crime scene is to make certain what appears to be a blood stain is actually formed of blood and not something such as catsup, paint or rust. A presumptive, or screening, test indicates whether or not a substance contains biological fluid. Such a test is often seen in television shows. A bit of suspected blood is collected on a swab, and a drop of phenolphthalin reagent is added to the swab. A drop of hydrogen peroxide is also added to the swab after a few seconds. When hydrogen peroxide is applied, an oxygen carrying molecule (hemoglobin) in blood causes a color change from clear to pink. One must not wait more than about 30 seconds to apply the hydrogen peroxide, however; by that time most swabs will turn pink merely from oxygen in surrounding air.
If the stain is determined to be blood, another possibility that must be considered is that the blood might not be human. Human blood is not the only blood that causes such a chemical reaction. Other primate blood does also. Subsequent confirmatory tests can determine if blood is human; but most presumptive-positive blood stain samples are usually simply sent to a laboratory for DNA analysis. DNA testing is specific only for human DNA. If a DNA analyst is faced with a mixture of saliva from a gorilla, which is a primate, and dog blood, it could confound matters a bit. It might provide an interesting plot twist, though.
What if one is relatively certain that a murder happened in a room, but there are no signs of a confrontation and no visible blood stains? As often depicted in television shows, in a darkened room, luminol can be sprayed onto suspected areas. Chemical reactions cause a blue glow that lasts for about 30 seconds and that is often bright enough to be photographed. The process enables even trace amounts of blood to be detected. Such a process is referred to as chemiluminescence. If you have ever seen fireflies or light sticks glow, you have witnessed the same chemical process. Some atomic electrons are caused to drop to lower orbitals where they have less energy. The energy previously associated with the electrons is released in the form of photons, the basic units of light.
As useful as it is, luminol is not completely successful in its intended use in finding invisible blood stains. For example, copper and its alloys, and even horseradish and fecal matter, can also cause a reaction that emits a blue glow. Some bleaches react similarly and, in a room recently cleaned with them, a resulting glow can mask the glow caused by blood stains. Unfortunately, luminol interferes with some other tests commonly performed. Fortunately, however, it does not prevent the extraction of DNA from suspected areas. Obviously, spraying an area with luminol would not be the first step in a crime scene investigation.
Additional Facts
Crime scene investigation is also referred to a criminalistics.
Blood in a typical human body at rest is fairly equally distributed in four general areas, namely, in the heart, lungs and large blood vessels; in blood vessels of the liver; in blood vessels of the muscles; and in blood vessels of other organs.
By weight, blood makes up about 8 percent of a healthy person’s total weight. An average woman has from 4 to 5 quarts of blood, and an average man has from 5 to 6 quarts. Incapacitation requires a loss of some 1.5 quarts, and irreversible shock (i.e., death) requires a blood loss of some 40 percent.
Bloody good, Amalgam! Didn’t know that about horseradish and fecal matter. So, an uncouth parent with a baby in diapers and a taste for spices might get away with murder. And I’m going to carry a measuring cup with me on my adventures now that I know I have 1.5 quarts of blood to throw around. As always, you are a lucid primary source for the rest of us, and you make complexities clear with deceptive ease.
Sully
Sully,
Once again, you have saved me from a long, cold trip to my office to post my blog. And you have posted a most complimentary comment that makes my piece pale by comparison. Thank you, thank you.
A percentage of attorneys and staff at my firm have been laid off, and my status has been changed to that of a contract employee. I still have an office but no salary or benefits. I get paid a percentage for whatever work I get. With less and less patent work coming in, however, I’m not likely to receive much. Hence, I visit my office only when there is work. Ah well, that should free up more time to write.
Amalgam
Terrific. I’m hoping to print out all of your blogs. Be well. Janet
Sully,
During an archaeology class, when I was taking regardless-of-the-weather, weekly, all-day-Saturday walks over rough terrain, I began to see not just what was around me but to understand its meaning and place in the Universe. As I began to take writing more seriously, I began to see more and more things that could lead to and fit into articles and stories. The rewards flowing from such experiences radiated not only into the realms of history and writing but into expanded views of life itself.
Your latest piece not only beautifully describes how such awarenesses can influence one’s writing, but ones entire life experience. And of course you did it in your unique style that makes a reader retain not only the ideas but often the very words describing them. Such were your highly visual and tactile phrases including “lariats of reeds” that snared you “as tightly as Chinese finger traps,” a “quid pro quo” of a chance meeting, and passing “stations of the cross,”
Throughout your piece, you urge readers to sharpen and extend their views and to “think outside the box,” not only regarding things they might see, touch and hear, but with experiences and their subsequent effects.
As usual, you illustrated your sentiments effectively by inviting readers to join you in but “a walk in the woods.”
You demonstrate your concern that writers might miss the importance of bringing out poignancy and meaning as doubts are being resolved. In addition, apart from the fine advice, you managed to house it all in an interesting account of an eventful day in your life (and mind).
Have no concerns about Flamingo Frank existing somewhere, my friend. He exists within all of us who knew him, and you have once again deftly demonstrated that he certainly exists within you.
I hope you have sent or will send a copy of your piece to Frank’s family.
Amalgam
For me, finding the right words is like finding the right notes when you whistle a song. In fact, it’s very much like whistling a song in slow motion, if that makes any sense. There is music to be had there, and when you point to things that communicated what I heard as I wrote, I feel justified. Thanks, Amalgam. And I do send my newsletter with the column links to Flamingo Frank’s family. His daughter Sheri often writes back, and of course the Wydra home and family have always provided sanctuary for me.
Sully
Janet,
Thank you for the compliment. ‘Tis a great feeling it gives me to know you would like such a collection.
I find it difficult to believe I’ve written as many of these pieces as I have. It seems as if I wrote the first one only a few weeks ago.
Take very good care.
Bob