Tools of genomic analysis have been used to assist the identification of victims of human rights violations. 1–4 Here we describe two recent applications, the identification of a young adult Argentinian born in captivity 22 years ago when his mother was abducted and disappeared in Buenos Aires in 1978, and the identification of remains found in mass graves in the Balkans in the 1990s. In both these situations we used DNA sequences to identify one individual among many (one child among many children; one body among many bodies) by genetically matching the individual to family members whose relative had disappeared.

Identical genomic information is carried by all tissues of a person, and thus is an inseparable source of personal identity. There are two genomes: nuclear and mitochondrial. Nuclear genes are inherited from both parents (Figure 1A); mitochondrial genes are inherited only maternally (Figure 1B). For resolving questions of identity in human rights contexts, mitochondrial DNA (mtDNA) is especially powerful, for several reasons. First, one purely maternal relative can provide information about an entire lineage. This is possible because a mother transmits her mtDNA sequence to all her children, male and female. Therefore, each person shares their mtDNA sequence with their mother, sisters, brothers, maternal aunts and uncles, maternal grandmother and her brothers and sisters, and so on. In many human rights investigations, only a few relatives survive to provide a record of genetic information. If the missing person (male or female) has one surviving relative to whom he/she is purely maternally related (ie related entirely through mothers),