Microscopy Applications for Forensics

Forensic DNA Profiling

Analyze Human Genomic DNA

DNA profiling has had a revolutionary impact on the work of law enforcement. The concept: a suspect's DNA is compared against genetic material either directly obtained at a crime scene or from a centralized database such as the Combined DNA Index System (CODIS). Human genomic DNA can be analyzed directly for individual identification and paternity testing on the basis of variations in its sequence.

The analysis of DNA isolated from forensic biological evidence provides valuable information relating to the identification of the source of the sample. This activity is based on analyzing the inheritance of a class of DNA polymorphisms known as "Short Tandem Repeats", or simply STRs. The polymorphisms in STRs are due to the different number of copies of the repeat element that can occur in a population of individuals. Whilst the method is highly selective, sample collection and the risk of contamination are highly challenging. Sample material can be any material on which biological matter is found.

Common biological materials for forensic DNA analysis are body fluids such as

  • saliva
  • sweat
  • semen
  • urine
  • blood
  • epidermal cells
  • hair
  • bone
  • tissue
  • fingerprints

Stereo microscopes are an indispensable tool in sample investigation. With a large stereoscopic field of view, easy usability, good ergonomics and natural reproduction of colors, stereo microscopes allow the quick and reliable inspection and digital documentation of biological materials on a variety of collected samples. Modern motorized zoom microscopes allow an even higher degree of resolution and automation when performing manual investigations, including options for fluorescence imaging. Dedicated fluorescence microscopes help to detect even the finest traces of DNA and complement the forensic workflow for pre-investigated samples. For contamination-free isolation and further molecular investigation Laser Catapulting Microdissection (LCM) is the ultimate tool to recover even the smallest amount of biological material.

Application Examples

Acquired with ZEISS Axioscope 5 and Sperm Hyliter BF
Vaginal swab
Acquired with ZEISS Axioscope 5. Courtesy of M. Schatzl, Dr. U. Schacker, Galantos Genetics Mainz, Germany
Sperm cell nuclei stained with DAPI
Acquired with ZEISS Axioscope 5. Courtesy of M. Schatzl, Dr. U. Schacker, Galantos Genetics Mainz, Germany
Sperm cell nuclei stained with Alexa

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