Why is Madeleine's hair so important?
Updated on 12 September 2007
Large amounts of Madeleine's hair was "found in the car boot", according to Portuguese police sources. If so, what can this reveal about Madeleine's disappearance?
Q. Why is Madeleine's hair so important?
A. Police sources have apparently told Portuguese press that "large quantities" of Madeleine McCann's hair was found in the boot of a car hired by her parents 25 days after her disappearance.
If this is true, the presence of hair may indicate whether Madeleine herself was present - and, it is argued, it may even help specify whether she was alive or dead at the time.
Alternatively, her hair may have been accidentally transferred to the car, or arrived via other sources.
Q. What does "large quantities" imply?
A. It has been argued that a large amount of Madeleine's hair in the car could only have come from her body, whether alive or dead, and so discounts the accidental transfer theory.
Q. What about other samples?
A. It is not yet known exactly what DNA samples have been found in the car. It is widely reported that bodily fluid with an apparent 80 per cent match to Madeleine was found inside the car. Subsequently it was claimed that a second DNA sample was found with a 99 per cent match.
"Bodily fluid" could refer to liquids excreted by a decomposing body, which would indicate the presence of a body, but not identify it. Alternatively, it might be trances of dried blood, which could prove it belonged to Madeleine.
Q. Can they tell whether Madeleine was alive or dead?
A. The DNA samples themselves cannot tell us whether they came from a live or dead source - but they can be used to identify whether or not they came from Madeleine.
Alan Baker, a forensic scientist who has given expert evidence on the subject of DNA in court cases said:
"DNA itself would not tell you if that person is dead or alive. If it was associated with bone fragments or a piece of tissue, that is another story."
Some experts argue that the state of decomposition of the hair samples themselves, could show whether they were taken from a living person or not. Hair taken from a deceased person decays in a different way to hair from a live person, but this could be affected by other factors - such as the temperature of the surrounding air.
