Several members of a family disappeared without a trace. Their bodies were eventually located buried in an isolated location several years after their disappearance. Although the bodies had decomposed to the point of being completely skeletonized, clothing and other articles potentially associated with the crime were located in and around the gravesite. Traditional swabbing methods were utilized on a number of items and no, or extremely limited, DNA results were obtained.
Ryan Forensic received several articles of clothing as well as electrical cords and tie-down straps used as ligatures. Each item of evidence had significant amounts of dirt, sand and debris present. Fabric breakdown common to clothing that has been buried for an extended period of time was also present, however most items were sturdy enough for aggressive sample collection. Initial testing with traditional swabbing and cutting methods presented no probative DNA results.
With no probative results to go on, several clothing items and ligatures were processed using the M-Vac forensic DNA (wet-vacuum) collection system. Particular attention was paid to areas on the clothing and ligatures that were folded or otherwise could trap and protect DNA material from degrading, and areas that investigators suspected perpetrator(s) would grab or touch in order to move the victims to the gravesites and to tie the ligatures. Samples were collected using the standard M-Vac collection method, then filtered and concentrated in the .45 micron PES filters. The filters were then processed using the Qiagen EZ1extraction method and analyzed on the AB 3500 sequencer at an accredited private DNA laboratory.
Quantification data revealed low-levels of DNA from the majority of the tested samples (generally 50pg or less) with the largest amount of DNA detected being slightly over 0.125ng total DNA from one clothing article. All samples were moved forward through DNA analysis, regardless of quantitation values. Resulting profiles were generally low-level and many were partial, however one sample did result in a nearly complete, mixed DNA profile.
On the advice of Ryan Forensic, the submitting agency submitted the low level mixed DNA profiles to CyberGenetics for TrueAllele probabilistic genotyping. Using probabilistic genotyping, comparisons between the profiles obtained from the evidence items and those of the victims and suspect in this case yielded meaningful and usable results which were entered into evidence during trial.
Even though the items had been buried, along with the victims, and were completely covered in dirt, sand, and debris, the M-Vac was able to collect enough DNA to obtain partial DNA profiles where original swabbing of the items yielded virtually no DNA results.
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Suzanna Ryan is a forensic serology and DNA expert. She owns Ryan Forensic and provides consulting and serology testing to many agencies. She has been using the M-Vac for a number of years to help solve difficult cases. If you would like a pdf copy of this article or additional information, please click here.