DNA-efterforskning
The use of DNA analysis of biological evidence from a crime scene or investigation to identify perpetrators, exclude suspects, or exonerate the wrongfully convicted through comparison with reference samples and criminal databases.
DNA-efterforskning refers to the investigative and forensic process of collecting, analyzing, and comparing deoxyribonucleic acid (DNA) evidence in criminal cases. In federal American criminal law, this encompasses both the initial collection and analysis of biological material from crime scenes—such as blood, saliva, hair, skin cells, or semen—and the subsequent comparison of DNA profiles against reference samples from suspects, victims, or entries in law enforcement databases like the Combined DNA Index System (CODIS). The investigative value lies in DNA's near-uniqueness to each individual, making it one of the most powerful identification tools in modern law enforcement.
In the context of post-conviction proceedings, DNA-efterforskning takes on particular legal significance through statutes governing DNA testing of preserved evidence. Federal law establishes specific procedures and standards for when courts must order DNA testing of biological material, particularly when such testing has the potential to produce new evidence that could challenge a conviction. The process requires that the evidence was not previously subjected to DNA testing, or that new testing methods could provide results that create a reasonable probability of establishing the applicant's actual innocence.
The procedural framework for post-conviction DNA testing requires applicants to demonstrate that the requested DNA analysis would produce materially relevant evidence and that the chain of custody of the biological material has been maintained sufficiently to ensure the integrity of results. If testing yields a DNA profile, federal standards may permit its upload to the National DNA Index System (NDIS) when it meets FBI quality and completeness requirements, potentially linking evidence across multiple cases or jurisdictions. This database comparison capability has proven instrumental in solving cold cases and identifying serial offenders.
In true crime discourse, DNA-efterforskning frequently appears in narratives of cold case breakthroughs, where decades-old biological evidence undergoes modern testing that was unavailable at the time of the original investigation. The term also encompasses the use of familial DNA searching, where partial matches in databases lead investigators to relatives of potential suspects, and genetic genealogy, where DNA profiles from crime scenes are compared against consumer genetic databases to construct family trees that narrow investigative focus.
The evidentiary weight of DNA evidence varies depending on the completeness of the profile, the size of the sample, potential contamination issues, and whether mixtures of DNA from multiple contributors complicate interpretation. Courts evaluate DNA evidence under established standards for scientific reliability, examining both the laboratory procedures used and the statistical probability calculations that express how rare the DNA profile is within the general population. Despite its powerful identification capabilities, DNA evidence alone does not necessarily establish guilt, as it confirms only that an individual's biological material was present, not necessarily their involvement in the criminal act itself.
