Dec 20 2017

Reducing Sexual Assault Kit Backlogs Using an Automated Protocol


Sorenson Forensics is a high-throughput private laboratory that processes hundreds of cases every day.  Much of our workload comes from backlogged sexual assault collection kits from across the country.   We “Y Screen” almost every piece of evidence in a kit, looking for presence of male DNA in female source samples.

Unfortunately for our lab, our highest volume test was also one our most cumbersome and manual to perform.  With ever increasing demand for testing, I was tasked with finding a better solution.   Implementing new chemistry and consumables, like Promega’s CaseWork Direct Kit and SlicPrep plates, combined with the automation power of Tecan liquid handling robotics, and the Accu-Placer, an evidence plate loading instrument, we were able to design a new process with a 4-fold increase to production capacity.


Written by: Jason Bryan, sorenson forensics


The Accu-Placer directs users to the well of a 96 well SlicPrep plate to accurately place each evidence snippet into the correct wells of the plate and records the scanned barcode.  The CaseWork Direct digest solution is added to each sample via Tecan liquid handling robotics, and the whole plate is incubated for about 30 minutes.

The SlicPrep plate is configured with a spin basket apparatus that allows for rapid separation of the DNA containing supernatant from the evidence substrate by simple centrifugation.  Lastly, the plate is processed through the liquid handling robot once more to set up the real-time quantitation reaction for DNA quantity estimations.  A batch of 80+ samples can be completed in about three and half hours, where batches of 30 were taking over 6 hours!  I was very excited to present our validation work for this new automated process in a poster at the recent ISHI meeting.

My expertise in high throughput lab design and robotic script development fit in perfectly with the automated Y screening project.  I began working for Sorenson Genomics (parent company to Sorenson Forensics) over ten years ago, doing DNA lab work and process design for high volume ancestry, paternity, and clinical diagnostic lab testing.  Through company changes, I have now been given an opportunity to apply my experience in forensics.  I’m very excited to learn and grow in this field.

Use of this newly developed automated protocol will significantly increase the amount of backlog cases our lab can work though.  With DNA, time after collection is very important.  DNA begins to break down under normal conditions and the amount of amplifiable material to work with decreases with time.  This can result in insufficient data to effectively match to potential perpetrators.   Many times these backlogged cases can be several years old. We hope with this new automated process we’ll be able to eliminate these backlogs, prevent new ones from forming, and help to bring long awaited justice for victims of sexual assault.