Även om man ställer termostaten på högsta värme i en ugn så finns inte förutsättningarna för att en pizza eller annan mat ska förorsaka en brand och även om maten långsamt förkolnar försvinner eventuella pyrolysgaser innan de uppnår antändningstemperatur. Inte heller fett och socker antänds då dessa kräver mycket högre antändningstemperatur än vad som kan uppnås i en ugn.
Kriminalteknikern Thor Kr. Adolfsen har i en intressant artikel i Bevis, den norska kriminaltekniska föreningens tidningen, noggrant gått igenom förutsättningarna för att mat ska kunna antändas i en ugn och konstaterar att det är en myt att så kan ske.
Artikeln finns tillgängligt i Bevis, kontaktorgan for Kriminalteknisk Forum, nr 1 – 2020.
Monday, February 10, 2020
Forensic researchers at the University of Surrey have debuted a new fingerprint test using high-resolution mass spectrometry (HRMS) that is sensitive enough to tell if an individual has ingested cocaine or merely handled it. The difference is critical when you consider the legal ramifications of ingesting the Class A drug versus being exposed to the drug by environmental factors, such as handling money.
In 2017, Melanie Bailey and her team utilized the HRMS method to detect cocaine in the fingerprints of drug users, but did not consider the fact that 1 in 10 non-drug users are exposed to cocaine through environmental factors.
In the current study, the researchers took fingerprints from persons who had testified to taking cocaine during the previous 24 hours. Fingerprints were collected from each patient, and the participants were then asked to wash their hands thoroughly with soap and water before giving another set of fingerprints. The same process was used to collect samples from a pool of non-drug users who touched street cocaine.
Cross-referencing the data, the researchers discovered that a molecule produced in the body when cocaine is ingested, benzoylecgonine, is essential in distinguishing those who have consumed the drug from those who have only held it. Benzoylecgonine was not present in samples from drug non-users, even after touching street cocaine and then washing their hands.
However, limitations to the method do exist. While it provides better selectivity and relies less on chromatography, it is lab-based and therefore cannot be used in a roadside test by law enforcement.
“At the roadside it would be possible to carry out a screening test, but you would still need to collect a sample to take back to the lab for confirmation,” Bailey told Forensic.
Additionally, the experimental test as comprised can only tell the difference between contact and ingestion of cocaine if a person has washed their hands prior to leaving a fingerprint.
“Hands do need to be washed to make that distinction,” said Bailey. “For fingermarks left at crime scenes, it would not be possible to distinguish cocaine contact from cocaine use without the hand-washing.”
The researchers believe there is potential for the HRMS method beyond forensic analysis. They are, for example, researching the possibility of using a fingerprint to test the therapeutic level of a drug to ensure medication is delivered at the correct dose. According to University of Surrey researcher Catia Costa, the team has already shown that antipsychotic medications can be detected in fingerprints, and research is ongoing.
Michelle Taylor Editor-in-Chief
New Webinar 11 Febr
Forensic Epidemiology: Monitoring Fatal Drug Overdose Trends
Given the vital role of medical examiners and coroners (ME/C) in recognizing emerging trends in drug overdose deaths, partnering epidemiologists with ME/C offices can greatly enhance the utility of the significant volume of data generated by medicolegal death investigation. Epidemiologists from three unique ME jurisdictions—North Carolina, New Mexico, and Virginia—share their experiences with monitoring drug overdose deaths, trends observed, and how best to utilize ME/C data to inform public health policy.
Detailed Learning Objectives:
1) Describe the potential role of epidemiologists in medical examiner offices and how they can assist in utilizing medicolegal death investigation data.
2) Understand current trends in drug overdose deaths as analyzed by three large statewide ME jurisdictions.
3) Understand the challenge of balancing state-mandated priorities with research and public health outreach.
För mer information gå in på: ForensicCOE <forensicCOE@rti.org>
Fingerprint Residues Can Reveal Their Age
Monday, January 27, 2020
A new proof-of-concept study that uses a highly sensitive mass spectrometry method to date fingerprints has its authors thinking they can test the promising methods in real criminal cases within the next few years.
In a preliminary new study published in Analytical Chemistry, researchers Paige Hinners, Madison Thomas and Young-Jin Lee from Iowa State University report they can link compounds contained in fingerprints with their age. While crime lab scientists have relied on fingerprints for over a century, pinning down the time the fingerprint was left has proven difficult. Knowing the age of a fingerprint can help investigators establish a better timeline, including ruling out a suspect or contradicting a suspect’s story.
Using prints collected from three donors, the researchers tracked shifting levels of triacylglycerols using matrix-assisted laser/desorption ionization mass spectrometry (MALDI-MS).
“Most compounds in fingerprint can be measured with this technique but we focused on triacylglycerols (body oil) as they are highly abundant and much more reliably measured than others,” Lee told Forensic.
The MALDI-MS results indicated the researchers could reliably determine the triacylglycerol degradation rate for each person over the course of seven days. But the rate differed among individuals, with one person’s triacylglycerols declining more gradually than the others. The researchers attribute this difference to higher levels of lipids in that individual’s fingerprints. The method also worked on residues that had been dusted with forensic powder.
“Ambient ozonolysis of fingerprint triacylglycerols has been recently shown by others, but it is the first time to show that it can be used to reliably measure the relative change of fingerprint composition over the first few days of deposition,” Lee said.
“This publication is still a proof-of-concept experiment, although very promising,” Lee said. “We just got new funding from the forensic program of the National Institute of Justice. We will continue to thoroughly study the fingerprint aging for multiple variables, such as environmental effect, individual differences, and experimental conditions.”
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