A complete match between the STR DNA profile of an evidence sample and that of an individual included in a database of profiles of convicted offenders has clear utility as an investigative tool. Very similar but nonetheless nonmatching DNA profiles also can provide useful information by suggesting that a close relative of the individual may be the source of the evidence sample. This article describes a general framework for determining the relative likelihood that an individual’s close relative is the source of an imperfectly matching DNA profile.