Can plants solve crime? The forensic value of plant evidence has long been known. Back in the 1930s, Edmund, the “father of forensics,” his locard reported that one rare dandelion seed on a murder suspect’s jacket drove him to the crime scene. Rocard had observed plants growing next to the corpse. This type of plant trace evidence is more valuable than ever in forensic investigations today and can include microscopic material from plant seeds, pollen, spores and their DNA.
Indeed, exciting recent advances enabling the detection and sequencing of trace amounts of DNA are providing conservation biologists and forensic scientists with new tools. Specifically, the detection of environmental DNA (eDNA) in water, air, dust, or soil samples can be used to identify the presence of plants, animals, and microorganisms that are otherwise not easily observable. Organisms, even while they are alive, release their DNA into the environment as skin particles, cells and fluids. When these DNA fragments are sequenced, they are matched to the DNA sequences of known organisms in eDNA reference libraries to provide identifying information. As with many microorganisms, the number of unique eDNA sequences provides an estimate of biodiversity even when comparative sequences from named organisms are not available.As environmental scientists have pointed out Eric Larson At the University of Illinois, this approach has value in detecting hard-to-observe and mysterious organisms such as rare species. Biodiversity levels can be estimated in important conservation sense, especially in light of climate change that threatens natural ecosystems.
“Recent and surprising advances in enabling the detection and sequencing of tiny amounts of DNA are providing conservation biologists and forensic scientists with new tools.”
eDNA technology improves the identification of traditionally studied organisms used for forensic examination of trace evidence (eg, pollen, fungal spores, and even plant tissue fragments). This method provides an opportunity to characterize the microbial fungal and bacterial components of a sample.One exciting path proposed by Sarah Ishak The Université de Sherbrooke links the characterization of leaf phyllospheres (microbial fungi that grow on plant surfaces such as leaves) to trace evidence samples. These fungi may be unique to plants because of their ‘assignment capacity’, the place and environment in which they were grown to provide an important link to the crime scene. Amaury Frank PhDs from Ghent University take this idea a step further and propose that plant eDNA in soil samples can be used to identify the specific vegetation communities from which the samples originated.
The promise of forensic eDNA
Does eDNA sampling have forensic value in criminal or civil cases? Forensic Botanist Mark Spencer We certainly think so, suggesting its value by providing crime scene geolocation, secret burials, and means to improve the “traditional” connection between suspect and victim. Proof-of-concept testing by Fabian Roger with the University of Zurich James Komori MIT of dust samples collected from the air showed that eDNA screening from probative objects such as clothing, vehicles, or instruments can be used to infer their geographic origin. Her eDNA of plants in the dirt on the suspect’s shoe soles could be traced back to the native vegetation at the crime scene.
Microbial identification determined via eDNA includes estimation of minimum post-mortem interval (PMI), identification of human suspects (via translocation of bacteria to surfaces), and toxicology cases (microbes involved in toxin degradation). has forensic uses in the identification of
Forensic eDNA applications are currently few but likely to increase as the approach becomes more widespread and is introduced into the forensic system. Standardization of methodologies and broader development of DNA databases are necessary to ensure that the results of eDNA applications are consistent, scientifically credible, valid and accepted as evidence.
Pioneering eDNA litigation
Pioneering forensic eDNA involved Asian carp 2010Chicago biologists were concerned that the opening of dams and weirs in the Chicago Area Waterway System (CAWS) would allow Asian carp to migrate from the Mississippi River basin to Lake Michigan. Asian carp is a highly problematic exotic fish that degrades the biodiversity of native fish in waterways. Imagine!). An eDNA test conducted by the U.S. Army Corps of Engineers confirms anecdotal sightings that live Asian carp were likely present in her CAWS, and at least some fish were found near Lake Michigan. It shows that
The US state of Michigan and five partner plaintiffs filed a lawsuit against the Army Corps of Engineers Require the construction of hydrological barriers between lakes and basins to stop the spread of Asiatic carp. Although eDNA evidence was a significant piece of forensic evidence considered in court, plaintiffs failed to prove the Corps’ failure to mitigate pollution (i.e., the presence of Asian carp in the Great Lakes). Therefore, the lawsuit was dismissed.
So can plants be used to solve crimes? When Edmond Rocard introduced the exchange principle in 1920, he emphasized the forensic value of materials identified in “les poussières organiques” (organic dusts). and linked suspects to victims and crime scenes. More than 100 years later, the examination of forensic trace evidence by eDNA testing is poised to take a step he probably never imagined.
