Did you know … Mitochondrial DNA can be extracted even when the cell is dead?

There is a tiny loop of genetic material called mitochondria dna (mtDNA). Each cell has one nucleus containing nuclear DNA (nDNA). However, each has 1000 to 2500 mitochondria. Because of the relative abundance of mtDNA in the cell, it can often be extracted from old or degraded samples in which nDNA is sparse. 

For example, if a piece of hair is found at a crime scene, the nDNA in it is sparse or too small. Because there are more  mtDNA in one cell, more of it is available to be extracted from the hair to find out who the hair belongs to and can help solve the crime. Another example is bone or teeth found in a decaying body. Bone and teeth in a decaying body contain very small amounts of dead nDNA which may not be enough to be able to be extracted or used. mt DNA which is a lot more in a cell can be extracted and used to identify who the body belongs to.