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Category Archives: crime lab

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.

 

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.

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More Info and List of Included Questions

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More Info and List of Included Questions

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More Info and List of Included Questions

 

Crime and Science Radio: Crime Scenes, Criminalistics, and the Cutting Edge

Crime and Science Radio: Crime Scenes, Criminalistics, and the Cutting Edge in Los Angeles: An Interview with Former LASD Criminalist Professor Donald Johnson of California State University, Los Angeles

BIO: Professor Donald James Johnson is an expert on criminalistics, with emphasis on crime scene investigation and reconstruction (homicides and sexual assaults), and forensic biology. His research interests include the application of new technologies to the field of criminalistics. He was formerly a senior criminalist at the Los Angeles County Sheriff’s Department, where he was involved in the scientific investigation of violent crimes.

NOTE: This show was recorded live at the MWA-LA Chapter meeting in Los Angels, CA

LISTEN: LISTEN: http://www.blogtalkradio.com/suspensemagazine/2016/09/10/crime-and-science-radio-with-special-guest-dr-donald-james-johnson

Link will go live Saturday 9-10-16 at 10 a.m. Pacific

LINKS:

California Forensic Science Institute: http://www.calstatela.edu/hhs/cfsi

School of Criminal Justice and Criminalistics at CSULA: http://www.calstatela.edu/hhs/crim

CSULA Masters in Criminalistics http://ecatalog.calstatela.edu/preview_program.php?catoid=11&poid=3452

Los Angeles County Sheriff’s Department Scientific Services video: https://www.youtube.com/watch?v=SboLJ7WwnXQ

Los Angeles County Sheriff’s Department: http://sheriff.lacounty.gov

American Academy of Forensic Sciences http://www.aafs.org

 

Q&A: Will a Decaying Corpse Actually Produce Alcohol?

whiskey glasses

 

Q: Is it possible or likely for blood alcohol levels to increase or decrease in a decomposing body, and if so during what stages of decomposition?

A: Alcohol is usually consumed in the decay process but may actually be produced and this might cloud any toxicological examinations on the corpse. Make it look as if the victim consumed more alcohol than he actually did.

I must point out that alcohol is not commonly produced but it does happen in rare cases. The alcohol is a byproduct of the action of some types of bacteria that are involved in the decay process. This means that alcohol can only appear during active decay. What is that time period? A little about putrefaction.

The decomposition of the human body involves two distinct processes: autolysis and putrefaction. Autolysis is basically a process of self-digestion. After death, the enzymes within the body’s cells begin the chemical breakdown of the cells and tissues. As with most chemical reactions the process is hastened by heat and slowed by cold. Putrefaction is the bacterially mediated destruction of the body’s tissues. It is this decay that might cause some alcohol formation. Not always, but sometimes. The responsible bacteria mostly come for the intestinal tract of the deceased, though environmental bacteria and yeasts contribute in many situations. Bacteria thrive in warm, moist environments and become sluggish in colder climes. Freezing will stop their activities completely. A frozen body will not undergo putrefaction until it thaws.

Under normal temperate conditions, putrefaction follows a known sequence. During the first 24 hours, the abdomen takes on a greenish discoloration, which spreads to the neck, shoulders, and head. Bloating follows. This is due to the accumulation of gas, a byproduct of the action of bacteria, within the body’s cavities and skin. This swelling begins in the face where the features swell and the eyes and tongue protrude. The skin will then begin to “marble.” This is a web-like pattern of the blood vessels over the face, chest, abdomen, and extremities. This pattern is green-black in color and is due to the reaction of the blood’s hemoglobin with hydrogen sulfide. As gasses continue to accumulate, the abdomen swells and the skin begins to blister. Soon, skin and hair slippage occur and the fingernails begin to slough off. By this stage, the body has taken on a greenish-black color. The fluids of decomposition (purge fluid) will begin to drain from nose and mouth. This may look like bleeding from trauma, but is due to extensive breakdown of the body’s tissues.

The rate at which this process occurs is almost never “normal” because conditions surrounding the body are almost never “normal.” Both environmental and internal body conditions alter this process greatly. Obesity, excess clothing, a hot and humid environment, and the presence of sepsis may speed this process so that 24 hours appear like 5 or 6 days have passed. Sepsis is particularly destructive to the body. Not only would the body temperature be higher at death, but also the septic process would have spread bacteria throughout the body. In this case, the decay process would begin quickly and in a widespread fashion. A septic body that is dead for only a few hours may appear as if it has been dead for several days.

As opposed to the above situations, a thin, unclothed corpse lying on a cold surface with a cool breeze would follow a much slower decomposition process. Very cold climes may slow the process so much that even after several months, the body appears as if it has been dead only a day or two. Freezing will protect the body from putrefaction if the body is frozen before the process begins. Once putrefaction sets in, even freezing the body may not prevent its eventual decay. If frozen quickly enough, the body may be preserved for years.

So, whether a particular corpse actually produces alcohol or not is totally unpredictable. How long it takes depends upon the conditions the corpse is exposed to. In a corpse in an enclosed garage in Houston in August, this process will be very rapid and the corpse will be severely decayed after 48 hours. If parked in a snow bank in Minnesota in February it might not even begin the decay process until April or May when the spring thaw occurs. And anything in between. The appearance of any alcohol would coincide with the time frame of the bacterial activity.

So how does the ME get around this possibility? How can he determine the actual alcohol level that was present prior to the decay process kicking in? He can’t with any absolute accuracy, but he does have a tool that will help him make a best guess. He can extract the vitreous humor from the victim’s eye—this is the jelly-like fluid that fills the eyeballs. The alcohol level within this fluid matches that of the blood with about a two-hour delay. That is, the level within the vitreous at any given time reflects the blood alcohol level that was present approximately two hours earlier. And the vitreous is slow to decay so it might be intact even though the corpse is severely decayed. By measuring the vitreous level the ME will know the blood alcohol level two hours prior to death and he can then estimate the blood alcohol level at the time of death.

 

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This question originally appeared in MORE FORENSICS AND FICTION

http://www.dplylemd.com/book-details/more-forensics-and-fiction.html

 

Crime and Science Radio Goes Live at MWA-LA

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Mark your calendars for this event. Jan and I are recording an episode of Crime and Science Radio live with our special guest Criminalist and Forensic Science Professor Don Johnson. This will be a fun and informative event. Sign up now.

From MWA-LA

We have a special luncheon planned in August:

D.P. Lyle and Jan Burke Live Radio Podcast with special guest interviewee Criminalist and Forensics Professor Don Johnson

This will be a unique opportunity to experience a live podcast with three outstanding experts

Sunday, August 7, 2016

Tam O’Shanter Restaurant

2980 Los Feliz Blvd.

Los Angeles

Doors open at 11:30

MORE INFO:

http://www.socalmwa.com/2016/05/tam-luncheon-dp-lyle-jan-burke-live-radio-podcast/

 

Crime and Science Radio: Forensic Science Then and Now: an Interview with Forensic Scientist Jay Jarvis

Join Jan Burke and Dr. Doug Lyle for an interview with prominent forensic scientist Jay Jarvis, who has over 35 years of experience in working in the field. He has served on the American Society of Crime Lab Directors/Laboratory Accreditation Board, and has written a history of the establishment of the first crime lab in Georgia. He currently operates a private forensic lab, Arma Forensics, which specializes in firearms evidence, and is active in his church and community. He’ll talk to us about forensic science, past, present and future; lab accreditation; firearms evidence; private labs, and more.

 

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BIO: Jay Jarvis is a native of Long Island, New York. While a student in high school, his chemistry class went on a tour of the New York City Police Crime Lab. It was on that trip that Jay decided that his interest in chemistry could be best used in the field of forensic science. After his family relocated to Georgia, Jay earned his Bachelor of Science degree in Chemistry from Georgia College. To better prepare himself for a career in forensic science, Jay applied for and was accepted into the graduate program in Forensic Chemistry at the University of Pittsburgh and received his Master of Science degree in 1979. Immediately after graduate school, he was hired at the Georgia State Crime Laboratory in Atlanta.

During his 32 plus year career, Jay either performed casework in or was a supervisor for most of the forensic disciplines. Between 1982 and 1997, he wore a multitude of hats, performing casework in firearms and tool marks, hair, fiber and glass comparisons, footwear and tire tread examinations, fire debris and explosives analysis, latent fingerprint processing, marijuana identification, presumptive blood testing and crime scene analysis for a large area of central Georgia. He has testified as an expert in Federal Court and the courts of Georgia and several other states over 750 times.

 

test fire rifle

 

Jay also has extensive experience in crime laboratory accreditation, having served as an accreditation assessor and as a member of the Board of Directors of the American Society of Crime Laboratory Directors Laboratory Accreditation Board (ASCLD/LAB), including one year as the Board Chair. He has been invited to speak at seminars and training sessions on topics related to forensic science. Jay currently lives in northwest Georgia just outside the metropolitan Atlanta area, which allows him easy access to most destinations via Atlanta’s Hartsfield-Jackson International Airport.

LISTEN: http://www.blogtalkradio.com/suspensemagazine/2016/03/25/crime-and-science-radio-with-special-guest-jay-jarvis

Link goes live Saturday June 4, 2016 at 10 a.m. Pacific

LINKS:

Georgia’s Crime Doctor http://www.lulu.com/us/en/shop/jay-jarvis/georgias-crime-doctor/hardcover/product-10639368.html

Arma Forensics http://www.armaforensics.com/index.html

Crime Lab Report  http://forensicfoundations.com/crimelabreport

ASCLD/LAB http://www.ascld-lab.org

“Real-Life Not Like CSI on Television,” Macon Telegraph article on Jay Jarvis http://www.armaforensics.com/uploads/Real_Life_CSI-Grisamore.pdf

“Alumnus carries microscope into career,” Georgia College Alumnus article on Jay Jarvis

http://www.armaforensics.com/uploads/Alumnus_carries_microscope.pdf

 

Can a DNA Sample Reveal Age?

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DNA found at crime scenes can be extremely useful in identifying a perpetrator. But this only works if they have a known suspect and a DNA sample from that suspect, or if the perpetrator is in the national DNA database—-CODIS. Without something to compare the crime scene DNA sample against, DNA is not very useful. Same can be said for fingerprints. But perhaps DNA offers something else.

Employing DNA obtained from a crime scene, Familial DNA has been used to narrow the list of potential suspects and this has proven useful in many cases—such as the famous Grim Sleeper serial killer. I have blogged on this before in cases such as The Boston Strangler and the amazing case of Yara Gambirasio.

DNA will of course reveal gender, but there is also research suggesting that race, hair and eye color, and physical features such as stature might also be determined from a DNA sample. These aren’t completely worked out yet but they are intriguing aspects of DNA analysis.

But what if a DNA sample could be used to determine the approximate age of the person? This would definitely help as, once again, it would narrow the suspect list. For example, if the crime scene DNA could be shown to have come from someone who was approximately 25 years old it would effectively eliminate a 60-year-old suspect. But is this possible? Maybe.

A new approach, using a process of gene expression called methylation, seems to offer hope. Researchers at the KU Leuven University in Belgium have developed a technique for assessing the degree of methylation in a DNA sample. They believe that this analysis will narrow the age range of the individual down to a four or five year window. If this proves to be true, law enforcement will have another useful forensic science tool.

 
 
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