SBM
This is not a good characterization of how IGG works (am experienced with amateur genetic genealogy).
JMO
"The Idaho state lab later located a single source of male DNA (suspect Profile) left on the button snap of the knife sheath."
Single source does not mean complete DNA profile. These are two completely different things. A single source could be complete or partial. At this point, all we know is that ISL found somewhere between 11 and 20 skin cells, of which a least some contained DNA, but we do not know what condition the skin cells were in and we do not know if a complete DNA profile could be or ever was generated from these cells. Usually it takes a minimum of 80 skin cells to get a complete DNA profile. And really more like 200 skin cells to start are needed in order to have 80 good skin cells with which to get the profile because the process destroys a lot of cells. There is new technology which is said to be able to get a profile from less than 10 cells but I have not been able to tell that ISL has it and I'm frankly worried about what may have happened to it at ISL - it should have been sent directly to Othram which has this technology. So, whether the DNA was degraded or there just simply was not enough of it to get a complete profile or even worse, the ISL messed up the DNA profile, IMO, it is unlikely to be a complete profile which is why Othram couldn't do anything with the DNA and the FBI took it after only 1 week and who knows what the FBI did, but, it probably wasn't IGG in one week especially without a report or name of the person who did IGG. And btw, Othram has state of the art technology to work with problematic DNA cases. So that's very telling that Othram couldn't do anything with the DNA. IMO, if Othram couldn't get anything from the DNA, no one could.
All JMO.
QUOTE
Single source does not mean complete DNA profile
A single-source DNA profile is a DNA profile that contains sufficient DNA from just one person1.
As the difference in the amount of the DNA contributed by the two sources increases, there becomes a point at which a clear major profile emerges that for all purposes can be treated as a single-source profile for interpretation and statistical calculations2.
Touch DNA in Forensic Investigation: Present Scenario
www.savvyforensic.com
TOUCH DNA IN FORENSIC INVESTIGATION: PRESENT SCENARIO
Touch DNA refers to the minute traces of DNA left behind when a person touches an object or surface. It typically consists of skin cells and other biological material transferred through physical contact. The development of highly sensitive DNA extraction and amplification techniques has enabled the collection and analysis of such low-template DNA, making Touch DNA an indispensable tool in modern forensic investigations.
Current Use in Forensic Investigations
1. Crime Scene Analysis:
o Touch DNA is used to identify potential suspects by analyzing items they might have handled, such as weapons, tools, or surfaces like door handles and countertops.
o It is especially useful in cases where no visible biological evidence, such as blood or saliva, is present.
2. Cold Cases:
o Advances in DNA analysis have enabled forensic teams to revisit old cases where Touch DNA could now provide new leads.
3. Violent Crimes:
o In homicides and assaults, investigators can recover Touch DNA from weapons, victim’s clothing, or ligatures, potentially linking suspects to the crime.
4. Property Crimes:
o In burglaries or thefts, objects like stolen goods, broken windows, or entry points are swabbed for Touch DNA to identify the perpetrator.
5. Interpersonal Crimes:
o In domestic violence or sexual assault cases, Touch DNA is used to establish physical contact between individuals.
Touch DNA: Collection, Analysis, and Procedures
Procedure for Collecting Touch DNA at a Crime Scene
Touch DNA collection requires meticulous techniques to preserve the integrity of evidence and prevent contamination. Below are the key steps involved:
1. Crime Scene Assessment:
o Investigators first identify objects or surfaces likely to contain Touch DNA. These include frequently touched areas such as door handles, weapons, tools, or clothing.
2. Personal Protective Equipment (PPE):
o To prevent contamination, investigators wear gloves, masks, and coveralls. Gloves are changed between samples.
3. Documentation:
o Photograph the evidence in situ and document its location and condition before collection.
4. Sample Collection Techniques:
o
Swabbing: The most common method, where sterile cotton swabs moistened with distilled water or buffer solution are gently rubbed over the surface.
o Tape Lifting: Adhesive tapes are pressed onto surfaces to collect microscopic particles, including DNA.
Standard methods of mixture analysis involve subjecting a dried crime scene sample to a “bulk” DNA extraction method such that the resulting isolate compromises a homogenized DNA mixture from the individual donors. If, however, instead of bulk DNA ...
pmc.ncbi.nlm.nih.gov
The ability to obtain DNA profiles from trace biological evidence is routinely demonstrated with so-called 'touch DNA evidence', which is generally perceived to be the result of DNA obtained from shed skin cells transferred from a donor's hands to an object or person during direct physical...
pubmed.ncbi.nlm.nih.gov