Criminal Forensics

油漆车辆交流期间留下的碎片cidents are valuable pieces of trace evidence for positive vehicle identification, especially in cases of hit and run.The composition and structure of paints and varnishes makes it possible to identify the car manufacturer and model involved in an accident, providing possible links to suspects.

Infrared microscopy is an established technique for multi-layer sample analysis. It allows paint samples to be characterized in detail, determining the thickness and composition of individual layers, making unambiguous characterization possible.

• Paints, Varnishes, Coatings
• Can analyze smallest particles using ATR (>2 µm)
• non-destructive method

Fibers and particles found at the crime scene can help build a picture of the crime, provide information about the criminal, and even exclude individuals from suspicion. Trace evidence found on an individual or on their property may link a suspect to the crime.

Infared (IR) microscopy allows characterization and positive identification of fine fibers and particles at micrometer scales, even where fibers are superficially similar. Natural and synthetic polymer types may be determined with ease by searching the comprehensive databases instantly gives identifies unknowns, e.g.:

• Natural and synthetic fibers
• Particles and their size distribution
• chemicals or coatings on fibers

Fingerprints are unique to an individual, making them among the most important pieces of physical evidence used in criminal forensics. Fingerprint evidence may link individuals to a crime or exclude others from consideration. Fingerprints are commonly classified into plastic prints, those left behind as indentations on soft surfaces; visible (patent) prints, formed when a person transfers a material like blood from their fingers to a surface; and invisible (latent) prints, which are left behind as the skins natural oils or sweat are transferred to a surface.

Latent prints are commonly imaged with the aid of powders or other chemical reagents. However, an alternative approach leverages the power of elemental mapping to characterize the fine detail of a fingerprint that may not be visible using other techniques. In this case, sweat left behind by a person touching a surface contains leaves a residue of different salts that are clearly visible through non-invasive micro-XRF spectrometry. Using a beam size of <20 µm,Bruker's M4 TORNADOmicro-XRF easily maps the distribution of elements in this residue thereby revealing the fine structure of a person's fingerprint. Sensitivity for these analyses can be fine-tuned through selection of appropriate anode compositions. A silver X-ray source is ideal for enhancing sensitivity for chlorine.

Reliable, robust detection of blood is critical to both reconstruct the dynamics of a violent crime and to determine the nature of the crime itself. Particularly on suspicion of a foul play, its detection can dramatically change the course of the investigations.

Over the last years Matrix Assisted Laser Desorption/ Ionization (MALDI) Mass Spectrometry Profiling and Imaging (MSP and MSI) have demonstrated to be suitable analytical tools as confirmatory tests for blood stains and blood marks as well as for determining blood provenance. MALDI MSP verifies the results of the currently applied presumptive (and thus unspecific) tests deployed at the scene and MALDI MSI yields vizualisation of blood in fingermarks through mapping blood specific proteins in fresh fingermarks. Further advancements have been made by mapping biomarkers of human and animal blood in old fingermarks, thus paving the way to examining cold cases.

在许多类型的证据,可能会离开behind at crime scenes, human hair is one of the most common. Hair is readily lost from individuals, left at crime scenes, or transferred between individuals when committing a crime. Forensic hair analysis commonly employs a comparative technique, where the physical and chemical features of hair taken during collection of evidence are compared with known samples. One such method of comparison is using elemental characterization of hair using micro-XRF.

Bruker's M4 TORNADOmicro-XRF spectrometer has been used to conduct detailed elemental analysis of hair to demonstrate this capability. Using a <20 um X-ray beam, analysis shows that hair compositions may contrast sharply between individuals for elements such as Ca, K, Fe and Cl. The ability to mine data within compositional maps was also able to demonstrate that compositions may even vary along a single strand of hair (e.g., Ca), suggesting bulk chemical methods may not accurately characterize the true compositions from an individual. The example demonstrates the power of Bruker microanalytical tools for forensic science.

Adhesive tapes are common targets of forensic examination in criminal investigations of kidnappings, homicides, and the construction of improvised explosive devices. While some tape characteristics may be discriminated with simple laboratory tools (optical microscope, solvents), more detailed approaches may be required that delve more deeply into tape and adhesive compositions and structure but enable retention the sample for additional tests or evidence storage. On some cases sample volumes are small, making material preservation even more important.

Bruker's M4 TORNADOmicro-XRF enables fully non-destructive spatially resolved elemental characterization of tape samples in minutes. With no sample preparation required, evidence sample integrity is retained. Workflows allow rapid comparative chemical composition analysis of evidence and reference samples. Software features enable reference compositional libraries to be built against which unknown samples may be directly compared and positively identified. With a large sample chamber, multiple samples may be analyzed together, providing rigorous evidence for criminal investigations.

Often times the most compelling evidence comes from the smallest details at a crime scene. X-ray Diffraction scans of trace powders from footprints, projectiles and vehicles can be compared to scans from samples collected at related locations or against known materials databases. Investigative organizations across the globe have turned to XRD as a valuable tool in their forensic toolkit.

Portable XRF
Bruker's TITAN and CTX XRF solutions for elemental analysis from Mg to U of solids and liquids in a fully mobile format. Used for rapid for identification of materials, or for fully quantitative compositional analysis.

TXRF
The field transportable S2 PICOFOX and lab-based S4 T-STAR total reflection XRF spectrometers for elemental analysis of liquids and solids down to sub-ppb detection limits without the need for complex lab infrastructure.

FT-IR and Raman spectroscopy
We offer a selection of compact and powerful spectrometers for on-site and laboratory analysis, providing fast and reliable chemical analysis of evidence.

FT-IR and Raman microscopy
asd For micro chemical analysis we offer a comprehensive portfolio of Raman and Infrared microscopes that are perfectly suited to analyze smallest traces as well as brittle or sensitive evidence

X-ray Diffraction
Crystallographic structure, material properties and phase analysis of crystalline and amorphous powders, bulk materials and thin films.