The link below is a 2017 project/study the DOJ supported and provides as a resource. It’s about Familial DNA Searching (FDS), and Partial Matches (PM) relating to unidentifed potential suspect DNA found at crime scenes. I am not a scientist and wanted to better understand how this all works and after going down many DNA testing related rabbit holes, thought this study was pretty clear/easy to understand. There’s a wealth of information in the resource and imo, is worth the read.
Lots of info forthcoming, feel free to scroll on by.
Some highlights (snipped):
II.
A Review of Familial DNA Searching
“The advent of familial searching is often linked to the use of varying stringency levels to conduct DNA searches. Although moderate stringency searches are the default search setting in CODIS, the software can be set to search at three different stringency levels: high, moderate, and low. High-stringency searches require all alleles to match exactly at all 13 CODIS markers or loci (see sidebar), whereas moderate and low stringency searches allow for the comparison of profiles that may be partially degraded and/or contain DNA from more than one individual (i.e., mixed sample) (FBI, n.d.; Steinberger & Sims, 2008). Moderate and low stringency searches may result in the identification of “partial matches” in which two profiles, although not an exact match, show a sufficient degree of genetic similarity to indicate that a potential familial relationship may exist (Steinberger & Sims, 2008).”
“The ability to identify familial relationships through lower- stringency searches has led to the development of two separate, yet related, practices known as FDS and partial matching (PM). Existing literature on these practices often refers to them interchangeably, making it difficult to decipher if and/or how FDS and PM differ. To help shed light on these practices, this section walks through the key characteristics that distinguish FDS from PM and reviews the landscape of existing definitions offered by various sources.”
Technology
“Although lower-stringency searches of DNA databases can uncover partial matches fortuitously, they are not ideal for deliberately identifying familial relationships. This is because low stringency searches can generate hundreds or even thousands of partial matches, none of which may be biologically related (Greely et al., 2006). Furthermore, CODIS may entirely miss partial matches that are actually related (Forensic Technology Center of Excellence, 2015). According to Steinberger and Sims (2008), “CODIS, in its current configuration, is a very poor tool for finding familial relationships” (p.31). In other words, FDS must be conducted “outside CODIS” because the original CODIS software was not designed to detect these types of relationships. Of the five states with publicly available policy documents explicitly allowing FDS, four of these administrative policies mention the use of specialized software to conduct the search. For example,
Colorado’s policy defines familial searching as “a deliberate search for biologically-related relatives of a contributor of an evidentiary profile conducted with specialized (non-CODIS) software designed for this purpose” (Colorado Bureau of Investigation DNA Familial Search Policy).”
III.
Definitions
“The definitions presented below are compiled from these multiple sources and by consensus with the roundtable members.
Familial DNA Searching: A deliberate search of a DNA database using specialized software (separate from CODIS) to detect and statistically rank a list of potential candidates in the DNA database who may be close biological relatives (e.g., parent, child, sibling) to the unknown individual contributing the evidence DNA profile, combined with lineage testing (e.g., Y-STR, mtDNA) to confirm or refute biological relatedness.
Partial Matching: A moderate stringency search of a DNA database using the routine search parameters within CODIS that results in one or more partial matches between single-source and non-degraded DNA profiles that share at least one allele at each locus, indicating a potential familial relationship between the known individual in the DNA database and the unknown individual contributing the evidence DNA profile.
Based on a review of the literature, coupled with themes from the expert roundtable, the above definition of familial searching draws on the general consensus that FDS is a deliberate or targeted search of a DNA database intended to identify close biological relatives of an unknown forensic profile. Central to this definition is the role that technology and lineage testing play in distinguishing FDS from PM. As evidenced by recent policy trends and assertions from expert roundtable participants, specialized software is critical for conducting true familial searches, whereas PM is conducted within CODIS as part of the routine search process, although it may be supplemented with additional lineage or statistical tests.”
**On page 13 of the document at link, there’s a graph I found helpful understanding how these processes work., tried to copy and paste the graph here, but it won’t work. Anyway, the graph outlines the steps in FDS and PM processes and what LE does once potential familial relationship(s) are supported and the identity/name of the CODIS profile is given to them (LE):
“Once the identity/name in the CODIS database is given to law enforcement, detectives perform additional investigation to try to determine which family member is the offender if there are multiple family member suspects (i.e., if there are 3 brothers). This may include constructing a family tree, examining official records (e.g., birth, death, school, marriage), and even reviewing social media profiles. In some cases the lab may perform this non-DNA research to further narrow down the suspects prior to releasing the identity of the family member in CODIS to law enforcement. Even at this late stage, the search could still hypothetically lead to no viable suspect being identified if, for example, a father’s family tree reveals no known sons after a father-son relationship is identified through FDS or if a potential suspect passed away between committing the crime and the familial search.
If a suspect is identified after this additional investigation, police must then gather evidence and collect the final confirmation DNA sample to test directly against the evidence DNA sample to confirm an exact match. Once a confirmation match is acquired, this will be the evidence used in court, and the case can subsequently follow a typical court process.
Discussions in the literature and media sometimes fail to note that the familial searching process is only intended to produce investigative leads (that are later confirmed or refuted by the testing of the suspect’s DNA sample).”
*** I assume that the glovebox DNA wasn’t specifically mentioned in the AA since iirc, LE stated they didn’t have results from SM’s vehicle back yet at time of BM’s arrest/AW issued. Also, I realize that the defense is claiming the DNA found on SM’s glovebox is “exculpatory” and trying to sway public opinion/create reasonable doubt to potential jury pool. It is more than evident to most of us that BM was/is the prime suspect since virtually moment one, everything points to him and LE never had/found compelling evidence of and/or pointing to any other suspects otherwise we’d have seen a very different posture by LE throughout the investigation. Having said that, LE can’t exactly ignore partial match DNA evidence and once the testing results on SM’s vehicle came back and LE was given the name of the SA in CODIS whose DNA was partial match to an unidentified person’s DNA found on glovebox, have deduced based on the info on the graph that once LE was given this info, as the graph indicates, they’d have likely reviewed other non-DNA information, and either 1.)
no viable suspects were identified or, 2.) if they were able to identify someone/relation, LE investigated them and they were able to
clear/rule them out i.e., person was not in Colorado when SM disappeared, had solid alibi etc., etc. It’s more than likely one of those two things above resulted upon further LE investigation, otherwise we’d have likely seen the prosecution drop the M1 and tampering charges against BM, which they didn’t and haven’t because IMO, the foreign unidentified glovebox DNA turned out to be not significant/not related to SM disappearance and is NOT exculpatory to BM. Which leads me to a question, is this DNA evidence even going to be allowed/admissible at trial? I don’t know how that works and don’t have time right now to look up.
But I do know that any competent DNA analysis expert witness will be able to explain it clearly to a jury at trial so they have a complete understanding of how it works, implications, collection procedures, testing procedures, usefulness/relevance to case, or in BM’s case, imo, it’s
irrelevance to the case.
https://www.ojp.gov/pdffiles1/nij/grants/251080.pdf
All of the above IMHOO
#FindSuzanne
#BringSuzanneHome
#JusticeForSuzanne
