Is forensic evidence sufficient to convict or acquit Kate and Gerry McCann for the possible killing of their daughter Madeleine?
The reported disappearance of Madeleine Beth McCann.
On May 3rd 2007 at around 10 pm, three-year-old Madeleine Beth McCann was reported missing, from an apartment in Praia de Luz, on the Algarve in Portugal. Various psychological, visual, auditory and forensic pieces of evidence have been discovered, which could convict the McCanns of Madeleine’s death however through various lawyers and many court cases in which they attack all those who even mention their possible guilt. Thus they have not yet been charged for her suspected death or her definite disappearance. However concentrating on biological and forensic evidence found during the Madeleine McCann investigation this research task will evaluate whether or not Kate and Jerry McCann should be found guilty for Madeleine’s disappearance or even death.
Cadaver dogs can be used as forensic tools in crime scene investigations (mostly when a victim is suspected to be dead), and they were used in the case of Madeleine McCann. Most of these dogs are highly trained air scent detection canines (Canis familiaris) and are more commonly used by law enforcement to detect narcotics, explosives or contraband in airports and other at risk places, these specially trained dogs are also used by the police, military, and civilian groups to locate missing people, as well as victims of disasters (natural and unnatural). A subspecialty of these scent detection canines is “cadaver searching” which uses canines to locate buried or concealed human remains. These dogs are carefully trained along with their handlers and have proved incredibly useful with regards to discovering missing or hidden human remains various blind field tests have been conducted, these tests simulated actual search conditions, and the dog’s recovery rates were between 57% and 100%, showing that correctly trained cadaver dogs make significant contributions with regards to locating and recovering human remains. (1)
These dogs detected both cadaver scent and the scent of blood in the room that the McCanns were staying in but also in a hire car which they rented 25 days after Madeleine’s disappearance. Portuguese detectives believe that the traces discovered are evidence that Madeleine McCann died in said apartment and then later her body was removed in the McCanns hire car, once police were no longer watching them as closely.
Two DNA samples found in the McCann’s hire car, were a match to Madeleine, one a full match and one an 88% match, this indicates that the samples came directly from Madeleine rather than from her belongings. A large amount of Madeleine McCanns hair was also discovered in the car hired by the McCann’s and police have stated that it is too great of an amount to have been transferred by the child’s blanket or clothes. The hair and DNA samples were found underneath the upholstery in the boot of the car, and a United Kingdom laboratory has confirmed that the traces found were definitely from Madeleine McCann. (2)
The technique used to test the samples is called “low copy number analysis” this allows scientists to find genetic fingerprints from tiny DNA samples. Jill Havern re-explained Gonçalo Amaral’s explanation of this analysis thusly;
“We all have 2 copies of every gene/stretch of DNA – 1 inherited maternally, the other paternally.
At some genetic sites, there are short, repetitive ‘motifs’ called markers. Each marker will contain a variable number of repeated motifs. In diagrammatic form, a marker pair at any one site, could be represented like this, where the letters, ACGT, are the 4 bases which make up DNA (AAGTC is an arbitrary motif);
Maternally inherited marker AAGTC|AAGTC|AAGTC|AAGTC|AAGTC|AAGTC|AAGTC|AAGTC| 8
Paternally inherited marker AAGTC|AAGTC|AAGTC|AAGTC| 4
So, at this marker site, the repeat pair values would be read as 8,4
The table above shows the way a unique profile of a child would be inherited from a given set of parental markers. The full set of 20 markers, in terms of 10 pairs of 2 values can be called the inherited genotype or genetic profile.” (3)
Therefore the exact sequence of the DNA is irrelevant. It is the number of motif repeats that is significant. Therefore, any reference to a small amount of errors occurring during amplification of the DNA (bulking up Low Copy Number (LCN) by copying a small amount of starting material) is irrelevant. The actual DNA code (ACGT) is of no interest, as long as its repeats of varying lengths, are present.
Even if a C is copied as an A, G or T, it does not affect this technique’s validity.