DNA solving
Investigative use of DNA traces to identify perpetrators and resolve cold cases
DNA solving denotes the investigative process in which biological traces from a crime scene are analysed and compared with known DNA profiles in order to identify a perpetrator or resolve an unsolved case. Under Danish law, it is not an independent legal term with a single fixed statutory definition, but describes a central investigative strategy in Danish policing and judicial practice.
In practice, DNA solving can take two primary forms: a direct match against DNA profiles held in police registers, or genetic genealogy, in which biological material from the crime scene is compared with profiles from publicly accessible DNA databases in order to find relatives of a possible perpetrator and thereby narrow the search to that person.
The method has proved particularly valuable in cold cases — that is, unsolved cases that may date back decades. A trace that yielded no results at the time of the offence may, decades later, be matched against a profile subsequently entered into the registers, or produce a result through extended genealogical work as such databases grow. Cases such as the Göhrde murders from 1989, which were solved precisely through DNA analysis of preserved biological material, illustrate the method's potential: traces preserved over decades can determine who was behind a crime, even when all other investigative leads are exhausted. A similar dynamic appears in the documentary series Evidence of Evil, where old forensic analysis forms the basis for renewed investigation.
In Denmark, the police were given an express legal basis for genetic genealogy in 2025 in the Danish Administration of Justice Act (retsplejeloven) § 754 f, which may be used only in cases concerning serious crime.
