 To better understand likelihood ratios, it is instructive to look at DNA evidence as a case study, focusing in particular on cold-hit matches. DNA evidence may be used to corroborate other evidence in a case or as the primary incriminating evidence. Suppose different investigative leads point to an individual, Mark Smith, as the perpetrator. Suppose the investigators also find several traces at the crime scene left by the perpetrator, and laboratory analyses show that the genetic profile associated with the traces matches Smith. In this scenario, the DNA match corroborates the other evidence against Smith. In contrast, suppose no investigative lead allowed the police to identify a suspect. The only evidence consists of the traces found at the crime scene. The police run the genetic profile associated with the traces through a database of profiles and find a match, a so-called cold-hit. Since in cold-hit cases there is no other evidence, cold-hit matches are the primary item of evidence against the defendant. Some scholars believe that this circumstance weakens the evidentiary value of the match. Others disagree. We now examine some of the main arguments in this debate.