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CASE SUMMARY

Case Synopsis:

An employee of a check cashing store arrived at work in the morning to open the store. Once inside he was confronted by two males at gun point. The two males were wearing gloves and their faces were covered. The suspects instructed the employee to open the safe and they retrieved the money and then fled.

Towards the rear of the store a rope was located hanging from the ceiling. Roof tiles had been removed and a hole had been cut through the roof. This location is where the suspects gained entry into the store. The suspects did not leave any evidence behind and no fingerprints were obtained due to the suspects wearing gloves.

Evidence Collected:

The white rope that hung from the ceiling to the floor inside the store was collected. Crime Scene swabbed the rope for contact DNA. These swabs were sent to the local lab where no DNA profiles were obtained by their procedures. The entire rope was then sent to DNA Labs International to use the M-Vac System collection method for contact DNA.

Laboratory Processing:

The entire length of the rope was processed with the M-Vac wet-vacuum collection system. The rope was coiled to provide for a wider surface for collection. The sterile surface rinse solution was sprayed down and collected from the course material. Then the liquid collected was filtered through a Nalgene Rapid-Flow Sterile Disposable Filter.

Once the filter was dry it was cut out from the container and prepped for DNA extraction. A Chelex extraction method was utilized and quantified with the Quantifiler® Duo DNA Kit. It was then amplified with Life Technologies AmpFℓSTR® Identifiler® Plus PCR Kit and analyzed on a 3130xL Genetic Analyzer.

Results:

The DNA profile obtained from this item indicates a mixture of at least four individuals contributing to a partial major male and minor DNA profile. The major DNA profile developed was sufficient for comparison purposes and CODIS entry. The current investigation is ongoing.

Journal of Cold Case Review

Volume 1, Issue 1, July 2015 Pg 26

An Official Publication of The American Investigative Society of Cold Cases

By Suzanna Ryan, MS

New Collection Technique – the M-Vac System

In order to get an informative DNA profile, whether it be through autosomal or Y chromosome analysis, first the analyst must be able to collect the DNA from the substrate. Traditional methods for collecting DNA from a particular sample or substrate include swabbing, cutting, or taping. A new method of sample collection is the The M-Vac system. The M-Vac is a wet vacuum collection system designed to be used on forensic evidence. Studies have shown that this system is able to collect more DNA than traditional methods (in one study, up to 180X more epithelial cell DNA was collected with the M-Vac system as compared to swabbing). In addition, the M-Vac system has shown to be useful in collecting DNA from large areas and is even able to collect additional DNA from samples that have already been swabbed.

Research studies on the M-Vac system conducted at UC Davis show that the M-Vac was able to collect male DNA from the shirts of female volunteers after males had merely grabbed the shirts. The M-Vac was compared to traditional swabbing methods and it was shown that M-Vac system was able to collect nearly 10 times the amount of male DNA than the swabbing method in one experiment. The M-Vac system was also shown to be useful in collecting male saliva from female volunteer’s skin even after the female had showered. While swabbing also yielded some male DNA from the skin of females after showering, the benefit of the M-Vac is that large areas are able to be sampled in a single sample, versus the comparatively smaller areas that may be sampled through swabbing alone.

A full copy of the journal is available at https://www.aisocc.com/journal-of-cold-case-review.html