Forensic DNA analysis

Parentage tests

Paternity investigations, maternity investigations, kinship cases, deficiency cases.

A parentage test is used to determine or rule out a suspected family relationship. In the case of deficiency, one of the persons involved is missing (e.g. in the event of death), in which case relatives of this person are included in the investigation as a substitute.

Identity investigations

An identity investigation is used to determine or verify the identity of an unknown corpse, body parts, blood samples or specimens from pathological examinations.
Identity testing can be carried out in two ways:

• By direct comparison with blood samples or oral cavity swabs of persons in question (i.e. the presumed identity) or their personal objects to which body cells are attached (e.g. hairbrush, toothbrush, razor, worn and not yet washed clothing).
• By examining close relatives of the person in question (i.e. the suspected identity) in the sense of a parentage investigation.

Trace examinations

Investigations to qualitatively determine the type of trace and to individualize the trace.

The trace examination first determines the type of trace: blood, saliva, semen, vaginal secretions.

The traces are then examined by means of DNA analysis to determine whether they can be assigned to a specific person as the perpetrator or whether a suspected person can be ruled out as the perpetrator.

Investigation methods

DNA is first isolated from trace and reference material.

Then various gene loci of the human genetic material that carry microsatellite polymorphisms are analysed using the polymerase chain reaction (PCR) and the individualizing characteristics are detected by capillary electrophoresis:

Various autosomal (i.e. all chromosomes except the two sex chromosomes) short-tandem-repeat (STR) polymorphisms are examined, which are individualizing when used in combination with the exception of monozygotic twins, as well as Y-chromosomal STRs, which are passed on in the paternal line of inheritance in males. The latter STRs are not individualizing (i.e. son, father, grandfather show similar characteristics), but are very helpful in difficult trace constellations (e.g. little trace material of a man mixed with abundant trace material of a woman).

Notes on preservation and dispatch

Official clients (e.g. police) have the appropriate expertise in handling samples for DNA analysis. However, we are happy to provide advice in questionable cases.

Private clients are requested to always contact us before preserving and sending samples so that we can advise them accordingly in advance.