A TYPE of genetic fingerprinting with a high chance of producing a false
match has helped to convict six people in the US. The increasing use of this
type of DNA evidence, based on DNA from the mitochondria of a cell, has sparked
heated debate about whether it should be admissible in court at all.
The genetic fingerprints most people are familiar with are based on the DNA
in the nucleus of the cell. Forensic scientists analyse more than a dozen
different chromosomal regions, so the chances of two people having the same
fingerprints are extremely low—in the order of a million to one.
But in some types of tissue found at a crime scene, such as hair without
roots, teeth, excrement and old bone, the nuclear DNA is too badly broken down
to analyse. In such cases, DNA in mitochondria, which carry their own genes,