Viral Fingerprinting as a Method of Identification

The research project started as a way to identify Finnish bones from World War II, lost for decades in the wilderness of the Soviet Union and finally brought home in the last 17 years. In total, 106 soldiers were recovered and DNA was extracted from their bones in hopes of identifying the unknown men.

Researchers from University of Helsinki and the University of Edinburgh were curious beyond basic identification and wanted to examine the DNA for viral infections as a method of studying the incidence of historic diseases. They selected Parvovirus B19 (which causes Fifth Disease) as it is a fairly prevalent virus and one that, once established, persists within the body. Many viruses are cleared from the body by the immune system following infection, but some viruses, like herpes viruses for example, form life-long latent infections that can be detected years after the initial infection.

Of the 106 subjects, 43 (45%) tested positive for one of two different strains of Parvovirus (there are three genotypic strains in total). In fact, upon further testing, while 41 men tested positive for one strain, the 2 men that tested positive for the second strain were found via mitochondrial and Y chromosome testing to be Russian in origin and not part of the Finnish army at all. Only the Finns tested positive for that specific strain, one that disappeared from Europe in the 1970s, but was known at the time to be a Northern European strain.

This research opens up some interesting ideas about geographic identification. We’ve previously discussed the use of strontium isotopes as a way of identifying where an unknown victim was born or recently lived. This technique would give researchers a way of following an individual through wherever he or she has lived and been infected by selective viruses. And as soft tissue in victims can quickly decompose, leaving behind the hardier bones for decades or centuries, a long lasting substrate for analysis could be a crucial part of identification.

Personally, I found this story interesting as the overwhelming majority of viral infections occur in the body’s soft tissues. Dengue virus, one of the viruses I study in my day job in the lab, has been identified for decades, but there is still much to learn about it, including which tissue and specific cells it infects. Many other viruses have similar questions. So far, this research has only been conducted on DNA-based viruses. RNA-based viruses, including dengue, are much more fragile, and likely would not be able to withstand the long-term conditions involved in this case. But under the right conditions, it is possible that RNA viruses might be extracted and identified. Something for discussion at lab meeting perhaps?

It’s been a hectic few months, so Ann and I are going to take a few weeks off to enjoy the holiday season, but we’ll be back on January 5th. Happy holidays to all!

Photo credit: AJC ajcann.wordpress.com

Forensic Case Files: 74 Years Later, the Dead of Pearl Harbor Come Home

Between June 8th and November 9th, 2015, the United States Defense POW/MIA Accounting Agency (DPAA) exhumed sixty-one caskets from forty-five grave sites at the National Memorial Cemetery of the Pacific in Honolulu. This action is part of a current effort to identify the hundreds of lost sailors from the USS Oklahoma, sunk on December 7, 1941, during the surprise Japanese raid that catapulted the U.S. into the Second World War. Four hundred and twenty-nine men from the Oklahoma were lost that day, but only thirty-five were identified in the years following the attack. The DPAA hopes to use modern forensic methods to identify the lost and return them to their families.

The Oklahoma boasted a crew of 1,300 on that sunny Sunday morning when planes appeared high above at 7:55 a.m. As the air raid siren screamed, men ran for the anti-aircraft batteries. But before they could make an attempt to bring down any of the incoming planes, the Oklahoma was hit by three torpedoes on the port side. The ship immediately started to list, but was then struck by another five torpedoes at 8:00 a.m. Due to the shifting position of the ship, several of the five torpedoes struck above the armor line, creating significant damage. A final torpedo hit at 8:06 a.m. as the ship continued to roll. The vessel completely capsized within twelve minutes of the first torpedo strike. Due to the speed of the attack and the considerable damage, hundreds of men were trapped inside the ship. Up top, many jumped overboard as the ship went down, while, inside, others attempted to escape through tiny portholes. However, the majority of the men trapped within the hull drowned.

Following their recovery in 1943, these men were buried in various cemeteries around Hawaii.  Later, in 1949, following the first laboratory attempt at identification, the dead sailors were moved to the National Memorial Cemetery of the Pacific.

Today, many of their remains have been exhumed and lie in the DPAA lab awaiting identification through modern means. Some may be identified by dental records, still more by DNA analysis, a tool unavailable decades ago. The bones are weathered, both by months or years in oil-saturated seawater before recovery from the Oklahoma, followed by burial in Hawaiian graves. Years-long interment in Pearl Harbor reduced the bodies to mere bones, and the remains of men who died in close quarters became co-mingled. However, worse, due to an assumption in the lab during the initial unsuccessful attempts at identification that re-internment would be in a mass grave, individuals were separated and their skeletal elements grouped by type (all the skulls in one area, etc.). When the lab workers were informed that the sailors were to be buried individually and were told to reassemble the remains, they were unable to do so. As a result, a single exhumed casket can contain the remains of up to ninety-five individuals. So the task of identification will now be a considerable challenge. Modern day forensic anthropologists hope to reassemble as many sets of remains as possible; DNA will accomplish the rest.

The DPAA hopes to bring home the missing and to bring closure to families, some of who lost two or even three sons who all served on the Oklahoma. So far, seven positive identifications have been made, but family notification is still forthcoming, so no names have been released yet. It is expected the project will take five years to complete, but the agency is hopeful that a minimum of 80% of the sailors will be successfully identified.

Photo credit: National Archives and Records Administration

Forensics 101: Forensic Toxicology

In blog posts over the past four and a half years (!), we’ve covered many aspect of the forensic study of death encompassing forensic anthropology, forensic pathology, forensic odontology, and including many of the techniques used in crime scene analysis such as fingerprinting, shoe and tire casting, and arson reconstruction. But one topic we’ve never covered that can be a crucial part of any death investigation is forensic toxicology―the analysis of chemicals and biochemicals that may be responsible for a victim’s death.

The body of knowledge required for the complexities of forensic toxicology is extremely broad. Not only does the toxicologist need to be familiar with thousands of toxic chemicals ―including narcotics, poisons, prescribed medications, alcohol, and environmental chemicals―but he or she also needs to understand how each of those chemicals interacts with the human body from ingestion through elimination, including the speed of metabolic processing. Not only does the chemical itself need to be identified, but the concentration must be determined as well, since many legal pharmaceuticals can become deadly poisons when taken in excess. The field of forensic toxicology takes into account aspects and methodologies from a number of sciences―analytical chemistry, biochemistry, epidemiology, pharmacodynamics, pathology, and physiology. It’s a very complicated science.

A toxicologist also needs to consider evidence found at the crime scene including prescription bottles, visible trace evidence, and drug paraphernalia. A half empty prescription bottle near the bed might not mean the deceased took all the missing pills at once, but a syringe of heroin still in a drug addict’s arm might indicate that looking at narcotics would be a good place to start the investigation into cause of death.

Often, however, the original chemical is not what the toxicologist looks for; instead, chemical breakdown products indicate a substance's original presence. And while we are mostly considering toxicology as contributing to cause of death, there are multiple uses of toxicology in live subjects as well, some of which we will consider below.

Multiple human samples can be taken for toxicology testing:

• Urine: While this is one of the most useful, non-invasive samples for drug testing, urine can’t indicate real-time impairment, only prior exposure to a drug. However, it can indicate the presence of chemicals up to several weeks after ingestion. Due to the private nature of sampling, regulations concerning collection must be put in place to avoid sample switching. Urine testing can be used with the living for real-time drug testing (ie. steroid use in sports) or post-mortem to help determine cause of death.
• Blood: As opposed to urine, blood can be used to substantiate the real time effect of a chemical. For example a blood alcohol level of greater than 0.08% indicates a dangerous and criminal level of impairment behind the wheel of a car. Blood testing is often the main way of determining toxic levels of drugs or chemicals in the deceased (ie. carboxyhemoglobin to prove carbon monoxide poisoning during a fire).
• Hair: Hair is used to prove long-time drug usage or to indicate exceedingly high dosages transferred from the blood steam. As human hair grows approximately 1 to 1.5 cm per month, the location of a drug in the hair shaft can indicate ingestion over long periods of time. Unfortunately, the characteristics of the hair itself can affect the results with coarse dark hair retaining more of any compound than fair, light hair, which can lead to suggestions of racial profiling.
• Gastric contents: Depending on the time of death following ingestion of poison or prescription medication, the stomach contents can contain high levels of drugs or potentially undigested pills.
• Vitreous humor: The vitreous humor is the fluid within the sphere of the eye. As it is isolated from the rest of the body, there is no chemical diffusion, and as the eye tends to putrefy more slowly than the majority of the body’s soft tissues, this allows needle sampling and chemical analysis in more decomposed victims.
• Maggot sampling: In victims that are found following a prolonged period after death and are in a state of advanced decomposition, sometimes it is not possible to test the body’s tissues. If flies have been allowed to land on the body and lay eggs, and a sufficient time has passed to allow maggot hatching and feeding, the maggots themselves may contain the toxic chemical that killed the victim. Analysis of the maggots themselves may reveal the chemical cause of death of the victim.

Since multiple sample types and many different compounds must be considered during testing, there are many different complicated analytical chemistry methodologies that can be used for the analysis including chromatography, spectroscopy, x-ray diffraction, immunoassays, and mass spectrometry. Despite the complexities, forensic toxicology can often be the field of science to determine cause of death when many other forensic specialties come up empty handed, leading investigators to a better understanding of the victim’s life and death.

Photo credit: Horia Varlan