The results can then be checked directly for matches with the reference material of suspects or with the database of the DNA analysis file (DAD) maintained by the Federal Criminal Police Office and may lead to the perpetrator.
How does this work?
The human organism is made up of a large number of different cells. The genetic information (DNA) is present in duplicate in almost every human body cell and is part of the cell nucleus. The DNA is present there in the form of structures known as chromosomes.
The information contained in the DNA molecules is determined by the sequence of four different building blocks - the so-called bases (A, T, G and C). The bases could also be described as the four letters of the DNA alphabet.
A relatively small proportion of human DNA material (approx. 2-5%) consists of the so-called coding regions in which the genes are localized. However, the remaining non-coding region (without genes) is the relevant region for forensic DNA analysis. This means that the method used here does not provide any information about a person's physical appearance (e.g. height, hair or eye color).
As a rule, samples are taken for analysis using a saliva sample from the reference person. However, it is also possible to obtain cells from blood, sperm, hair roots or other body tissue, for example. During the analysis, DNA sections are examined that occur in all people but can be of different lengths.
By determining the length of several of these DNA sections in parallel, a special combination of numbers is obtained, which is also known as a DNA identification pattern.
High evidential value
Statistically speaking, a pattern obtained in this way only occurs once among more than 500 billion people not related by blood. If all the DNA characteristics examined match completely, it is possible to assign a trace to a reference person.