Författararkiv: Jan Olsson
Skyddad: Journal of Forensic Identification 2020 – 2
Pizzabränder bör förebyggas, men ingen omkommer genom dem
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.
Skyddad: Journal of Forensic Identification 2020 – 1
Fingeravtryck kan avslöja missbruk eller annan kontakt med kokain
Forensic®
Fingerprint Test Can Tell if a Person Used Cocaine or Simply Touched it
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
https://www.forensicmag.com
Skyddad: Journal of Forensic Identification 2019 – 4
Residues Can Reveal Their Age
Fingerprint Residues Can Reveal Their Age
Monday, January 27, 2020
Editor-in-Chief
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.”
https://www.forensicmag.com/560151-Fingerprint-Residues-Can-Reveal-Their-Age
Kongressrapport om behovsbedömning för att underlätta samordning och samarbete inom kriminalteknisk vetenskap i USA – från den federala regeringen ner till statliga, regionala och lokala verksamheter.
Med hjälp av ett systembaserat tillvägagångssätt som ett organiserande och förenande tema berör denna rapport det kriminaltekniska systemet som helhet, från den utbildning som krävs för nuvarande och framtida personal, till arbetsbelastning och infrastrukturbehov, till processen att väcka ett ärende att pröva från både försvars- och åtalsperspektiv.
Vill du få del av rapporten kontakta jan.olsson@forensic.se
