Biology

 DNA evidence for blood test
Index for the DNA sample of Group 1
From left to right-
Reveilles blood sample (a)
M. flash shirt(a)
M. flash DNA  (b)
Biker man shirt(c)
Biker man DNA (c)
Ladder (l)
Reveille fur (a)
Results

1. From the fingerprint test, it can be assumed that the culprit could be Maroon Flash.

2. The presumptive blood evidence indicates the presence of human blood on Reveilles fur collar,  
the Biker mans shirt and Maroon Flashs shirt.

3. The DNA fingerprint results from hair and blood sample definitely incriminates Maroon Flash as the bands in the gel or the distance traveled by the DNA fragments obtained from Maroon Flash exactly match those from Reveille.

Inference
From these results it can be concluded that there is sufficient evidence to focus on one subject for further investigation. The results of the DNA fingerprint test clinch the evidence incriminating Maroon Flash as the DNA from his shirt match those exactly of Reveille. Hence, the evidence indicates that one of he is lying about hitting Reveille.

The three variables that influence the distance that DNA fragments move through an electrophoresis gel under the influence of an electric motive force are
The mass of the DNA fragments- the heavier or larger the fragments, the lesser the distance moved.
The porosity of the gel or inversely, the concentration of media used which would not allow bigger molecules to cover more distance through its mesh network.

The third factor is the e.m.f. charge and the time for which the current has been allowed to pass through the gel electrophoresis setup.

Forensic experts compare crime scene evidence to reference materials or samples obtained from suspects is because the DNA fingerprinting technique has been developed to such an extent that it can be used to distinguish between two individuals of the same species. The charge to mass ratio of all species is the same (Z) but the bands obtained by passing e.m.f. through a gel containing DNA samples from victims or potential crime scenes, gives an uncanny rate of success in implicating or exonerating a suspect. Variability in Short Tandem Repeat sequences can be used to distinguish one DNA profile from another. Hence, in recent times DNA fingerprint evidence has gained immense popularity in not only solving criminal cases but also unresolved paternity cases.