Its a given that any unknown DNA found anwhere at JBR's crime scene adds to the IDI argument, especially if it is found in a conspicuous place. And it was found in a conspicuous place, was it not?
not so fast,Hold.it's a
partial profile.I'll repeat myself here:
All technology has limitations. For multiplex PCRs, the most serious limitations are in the areas of samples that are minimal, degraded, mixed, over-interpreted, contaminated or even potential combinations of these. Some current practices lack support by the established literature.
Over-interpretation can also occur when there are partial profiles.[1] The scientific system recognizes the human tendency toward over-interpretation and offers the countermeasures: independent review, independent verification, scientific controls and demonstrations of reproducibility. These reviews and controls are considered integral parts of the scientific process.
PCR-based testing is potentially useful since it is currently the only quick method of amplifying really minuscule amounts of DNA
. However, it is important to recognize that PCR based methods are exquisitely sensitive to contamination and need to be interpreted with extreme caution. Match probabilities generated with some STR typing systems may involve extreme numbers perhaps giving the impression of an infallible result. Scientific rigor often requires that extreme numbers be placed in a context that considers all aspects of testing including laboratory error rates and technical limitations.
Partial Profiles
Use of "partial profiles" is a newly emerging and fairly disturbing trend. A partial profile is one in which not all of the loci targeted show up in the sample. For example, if 13 loci were targeted, and only 9 could be reported, that would be termed, a partial profile.
Failure of all targeted loci to show up demonstrates a serious deficiency in the sample. Normally, all human cells (except red blood cells and cells called "platelets") have all 13 loci. Therefore, a partial profile represents the equivalent of less than a single human cell.
This presents some important problems:
1.
A partial profile essentially proves that one is operating outside of well-characterized and recommended limits.
2.
Contaminating DNA usually presents as a partial profile, although not always. For this reason, the risk that the result is a contaminant is greater than for samples that present as full profiles.
3.
A partial profile is at risk of being incomplete and misleading. The partial nature of it proves that DNA molecules have been missed. There is no way of firmly determining what the complete profile would have been, except by seeking other samples that may present a full profile.
Most forensic laboratories will try to obtain full profiles.
Unfortunately, in an important case, it may be tempting to use a partial profile, especially if that is all that one has. However, such profiles should be viewed skeptically. Over-interpretation of partial profiles can probably lead to serious mistakes. Such mistakes could include false inclusions and false exclusions, alike. It could be said that, compared to the first PCR-based tests introduced into the courts,
use of partial profiles represents a decline in standards. This is because those earlier tests, while less discriminating, had controls (known as "control dots") that helped prevent the use of partial profiles.The earlier tests will be discussed below, primarily for historic reasons, but also because they do still appear on occasion.
RDI would be better off leaving the DNA alone, because its sooo obvious that these RDI 'explanations' (factory worker, shared toilets, CODIS can't tell its not a family member, please!!) are really just automatic RDI knee-jerk concoctions that would've been instantly applied to any unidentified DNA found anywhere at the crime scene.
oh my my,you do wish,don't you.
Now as I said before,BR was a MINOR at the time,so even if some or all of the dna from that partial profile matched his,that wouldn't be publicly released.It could still be called unknown as well,since it isn't a full profile,and since BR and JB were brother/sister,and the dna was mixed and incomplete,it could contain shadowbands/stutter dna from each,and be difficult if not impossible to determine who's dna belonged to whom.
