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Category Archives: High Tech Forensics

Can Your DNA Reveal Your face?

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You’ve seen it on TV. The CSI-types plug in a DNA sample and like magic a 3-D, holographic image of the bad guy pops up like a ghost. Or some such stuff. Pretty far-fetched. Or is it?

DNA analysis is primarily used for comparison, meaning that a sample obtained from a crime scene is compared with a sample obtained from a suspect to see if the DNA from the scene belongs to the suspect, or not. This is how many cases are solved. DNA is highly accurate for making such comparisons.

But what if there is no suspect and therefore no DNA to compare with that obtained at the crime scene? The police will then go to databases such as CODIS to see if the perpetrator has DNA on file from previous crimes. Often this helps. Often a match is made this way. But what if the perpetrator is not in the system? The police are back to square one.

DNA can of course reveal the sex of the individual very easily. It can also often determine hair and eye color and other physical features. But can it give a “picture” of the individual who left the DNA behind? Not yet, but things are moving that way.

Here are a few fun articles on this technique:

DNA Phenotyping Recreates the Face of an Alleged Serial Killer: https://www.forensicmag.com/article/2016/08/dna-phenotyping-recreates-face-alleged-serial-killer

First DNA-Phenotyped Image of “Person of Interest” in Double Homicide: https://www.forensicmag.com/article/2015/01/first-dna-phenotyped-image-person-interest-double-homicide

Phenotyping and Cold Cases:
https://www.defrostingcoldcases.com/phenotyping-cold-cases/

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Bugging Your DNA

Mosquito

 

Everybody hates mosquitoes. They irritate, they bite, and they carry disease. In fact they are likely the most deadly creature on Earth since they spread malaria through many regions of the world. They also spread things like yellow fever and Zika – – – and a host of other nasty little problems.

But can mosquitoes place you at a crime scene? If so, how would this work?

Let’s say investigators come to a murder scene and find a smashed and dead mosquito on the bed sheets near the corpse. It might be reasonably assumed that this mosquito bit someone and that person then killed it, leaving it where it fell. Could that be used to ID the killer?

It appears that human blood can remain in the mosquito’s stomach for up to two days. And if this is extracted, it can be used in DNA profiling. So the mosquito at the crime scene could be collected and tested, and if DNA were found, a profile could be generated and lead back to the killer.

Esoteric, but fascinating.

 
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Posted by on August 31, 2017 in Crime Scene, DNA, High Tech Forensics

 

Luminol and A Malarial Drug Team Up to Find Hidden Blood

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Sometimes blood shed at a crime scene is easily visible but at other times less so. Maybe it’s a very small amount, or perhaps soaked into a patterned carpet, or secreted in the gaps between tiles and baseboards. Perhaps the killer has cleaned up the crime scene, thinking that if the blood is not visible, it’s not findable. Maybe he even washed the blood off is hands and watched it circle down the drain. Gone forever.

Or maybe not. Things such as luminol can uncover these hidden stains.

Luminol is actually quite sensitive for finding blood. Spraying it on a wall that has been wiped clean of visible blood, or often even if painted over, and then turning out the lights will reveal the glowing pattern of the blood splatter. This helps not only to locate the blood but also to identify patterns, which, in turn, might help re-create the crime scene. Such reconstructions are critical in bloody homicide investigations.

From FORENSICS FOR DUMMIES:

Reconstructing the crime scene from bloodstains 

Contaminated evidence is no evidence at all, so investigators have to document bloodstain and spatter patterns in a timely and logical fashion. Police, fire, and rescue personnel can alter or contaminate the blood evidence, as can any unnecessary foot traffic at the crime scene. For that reason, investigators need to take control of the scene immediately and consistently. 

Unless they’re high‐traffic public places, indoor scenes usually can be preserved long enough for investigators to obtain needed information. Outdoor scenes, however, are subject to environmental influences, and public places require investigators to gather information more urgently. 

Investigators carefully photograph bloodstains. Initial photographs capture an overall view of the scene. Subsequent pictures gradually move in on individual stains. The photographer takes pictures of individual stains close enough to reveal all needed detail, and should include a ruler or other measuring device to provide a scale reference. In homicide cases, investigators check out the body and any associated bloodstains or spatter first. After the body is removed, investigators turn their attention to other spatters. 

Some bloodstains are latent (invisible to the naked eye). Investigators often use luminol to expose these hidden stains. Luminol is a chemical that reacts with the hemoglobin in blood to produce a complex substance that luminesces (glows). Luminol is extremely sensitive, detecting blood in concentrations as low as one part per million. Investigators darken the room and spray luminol over areas where they suspect blood to be. When blood is present, stains glow a bluish‐white, and the photographer takes pictures of the glowing pattern. 

Luminol also can reveal bloody tracks that indicate the perpetrator’s movements or escape route and drag marks that show whether anyone moved the body. Luminol is so sensitive that it can uncover blood in cracks, crevices, and even areas where someone has tried to clean it. 

It’s important to note that many substances can interfere with or confuse luminol pattern analysis. Bleach and other cleaning agents, certain paints and varnishes, and even some fruit juices are examples. 

After photographers take an adequate number and variety of photographs, crime‐scene analysts complete their analyses and create a report that may include implications of the victim’s and assailant’s locations at each stage of the crime, the number and types of injuries inflicted, and the exact sequence of events (see the next section to understand how analysts gather this information).

But, as mentioned above, there are things that interfere with this chemical process. Certain fruit juices, bleaches, horseradish and turnips, and other chemicals will also react with luminol and this can confuse the issue.

A recent study reported in Science Daily suggests that a new method might help solve some of these problems. Combining luminol with the antimalarial drug Artemisinin seems to reduce this cross-reactivity and therefore more specifically display the true blood spatter pattern. Obviously, more research is needed, but this is a potentially useful tool.

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How Old Is That Fingerprint?

Fingerprint

Fingerprints are useful forensic science tools. They’ve been so for over 100 years. Mainly, it’s the pattern of the ridges on the fingertips that supply the useful information. We know that everyone has different fingerprints and we know that they do not change throughout the person’s life. This means that they are highly reliable sources for identification and for discrimination between two individuals. Law enforcement has employed this for years.

But several newer techniques and analyses allow investigators to go even deeper. The skin cells, that are part of a fingerprint, can often yield DNA. Chemicals in the print residue can sometimes reveal if the person has used or handled such substances as cocaine. Other analyses are underway that might make fingerprints even more useful.

One question that frequently plagues crime scene investigators is exactly when a print was laid down. This determination can make a huge difference. Let’s say that a print is discovered at a homicide scene and the primary suspect says that he had been at that location but that that had taken place a week earlier. Not on the day of the killing. Is he telling the truth? Or simply trying to throw the police off and make an excuse for the evidence they collected against him? It would be nice to know if the print was 24 hours old or seven days old.

Research is currently underway by Shin Muramoto and his colleagues and they reported their initial findings in a recent article in Analytical Chemistry. They discovered that a chemical found in fingerprints known as palmitic acid migrates away from the ridges at a predictable and consistent rate. By looking at this migration pattern they are able to determine whether the print is fresh or up to four days old. They are looking to extend this envelope to a longer period of time. But you can see, that even this level of discrimination could help—or not—- the suspect in the above scenario.

 

Can Your Pacemaker Snitch On You?

Don’t you just hate it when your pacemaker snitches on you? I mean, apparently all you wanted to do was burn down your house and collect the insurance money but then your pacemaker spoke up. Your plans went up in smoke – – no pun intended.

Pacemakers surely have changed since I was in medical school. Back then, they had to be inserted in the abdomen and the pacemaker leads shoved up through the diaphragm where they were screwed into the heart muscle. It was a major procedure, done under general anesthesia. The device weighed around a pound and only lasted 12 to 18 months. Then you had the pleasure of doing it all over again.

Also, back then, pacemakers were mostly a safety net. They were used for people who had very slow heart rates, even episodically, to prevent dramatic drops in the heart rate that could lead to dizziness, falls, and loss of consciousness. Pacemakers were often set at 60 to 70 beats per minute which meant that your heart rate could never fall below that. The pacemaker would sit and watch the rhythm and any time the rate dropped below these parameters, the pacemaker would kick in and supply the electrical impulse the heart needed.

Things are much different now. Today’s pacemakers are small, about the size of a wristwatch in many cases, last a decade or more, and will do much more than simply provide a safety net. They can help regularize abnormal rhythms, increase heart rate in response to exercise, and do a myriad other things to make them more efficient and helpful.

They also store data. This means that the pacemaker can periodically be interrogated and everything that has gone on in the individual’s rhythm over the past few months is available for analysis. And some of the newer models actually send the data to a central monitoring station in real time. My how things have changed.

For Ross Compton, his pacemaker, which was of course equipped with all this new technology, just might have snitched on him. According to investigators, Compton allegedly torched his house, likely in an insurance scam. He said that once he saw the fire he began unloading his most important belongings out a window and ferried them to his car. It was a real fire drill of sorts.

However, when his pacemaker was interrogated it showed no changes that would be consistent with such frenetic activity. No arrhythmias, no high heart rates, nothing to suggest extreme physical activity during the time in question. Had he actually been lugging stuff out the window and racing to his car one would expect that his heart rate would be greatly elevated from the exertion. Apparently, that’s not what was found.

It’s going to be interesting to see how this case turns out.

 

Crime and Science Radio: Facial Recognition and Other Biometrics with FBI Senior Photographic Technologist Richard W. Vorder Bruegge

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BIO: Richard W. Vorder Bruegge is a Senior Photographic Technologist at the Federal Bureau of Investigation where he is responsible for overseeing science and technology developments in the imaging sciences.  He has an Sc.B. in Engineering, and an Sc.M. and Ph.D. in Geological Sciences from Brown University. He has been with the FBI since 1995, where he has performed forensic analysis of image and video evidence, testifying in state, federal and international courts as an expert witness over 60 times.  Dr. Vorder Bruegge was chair of the Scientific Working Group on Imaging Technology (SWGIT) from 2000 to 2006 and chair of the Facial Identification Scientific Working Group (FISWG) from 2009 to the present.  He is a fellow of the American Academy of Forensic Sciences (AAFS) in the Digital and Multimedia Sciences Section.  In 2010 he was named a Director of National Intelligence (DNI) Science and Technology Fellow for his work in facial recognition.  He is currently Chair of the Digital/Multimedia Scientific Area Committee in the Organization of Scientific Area Committees (OSAC).

LISTEN: http://www.blogtalkradio.com/suspensemagazine/2017/04/01/crime-and-science-radio-with-special-guest-richard-bruegge

Link will go live Saturday 4-1–17 at 10 a.m. Pacific

LINKS:

Biometric Center For Excellence (BCOE): https://www.fbi.gov/services/cjis/fingerprints-and-other-biometrics/biometric-center-of-excellence/modalities

Facial Identification Scientific Working Group (FISWG): https://www.fiswg.org

FBI Caught On Camera: https://www.youtube.com/watch?v=u5Oj2FDwLXs

 

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Check out the new posts John Raab of Suspense Magazine and I put together. Read the Q&As and listen to the expanded discussions. Hope each proves helpful for your crime fiction.

Can DNA Be Used To Identify Multiple Assailants In a Three Decade Old Rape?

http://suspensemagazine.com/blog2/2016/12/20/d-p-lyles-forensic-file-episode-1/

In 1863, Could An Autopsy Accurately Determine the Cause of Death?

http://suspensemagazine.com/blog2/2017/01/09/in-1863-could-an-autopsy-accurately-determine-the-cause-of-death-d-p-lyle-answers-this/

Can My Female Character Cause Her Pregnancy To Become “Stone Baby” By Shear Will?

http://suspensemagazine.com/blog2/2016/12/31/can-my-female-character-cause-her-pregnancy-to-become-stone-baby-by-sheer-will/

More to come.

Want more cool questions from crime writers? Check out my three Q&A books.

M&M 200X300

More Info and List of Included Questions

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More Info and List of Included Questions

MF&F 200X320

More Info and List of Included Questions

 
 
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