Date of Award
Master of Science (MS)
Linda Chiu Rourke
A previously developed, non-destructive, homemade vacuum method for collecting biological material from handwritten documents had promising DNA results for white copy paper, preserved indented writing, and latent prints. Prior to casework implementation, additional validation experiments are warranted and here the method was tested for different paper substrates. This work describes testing of notebook paper, bank deposit slips, magazine pages, and manila envelopes. The quantity of recovered DNA varied from donor to donor, but the mean quantities showed a trend that can be explained by the different sizes and surface properties of the tested paper types. The rougher paper type, like manila envelopes, yielded the most DNA, while the smaller deposit slip yielded a lower amount of DNA. Magazine paper was very thin, difficult to handle, and not ideal for DNA recovery. Furthermore, the exact manual vacuum method technique was important. A single pass with the pipette opening (“single pass vacuum method”) yielded less DNA than slowly and methodically going back and forth over the same area (“double back vacuum method”), for each horizontal pass. Paper samples obtained from an additional 10 volunteers, processed with the “double back vacuum method”, yielded enough DNA (≥4 pg/µl) from copy paper (7/10), notebook paper (6/10), deposit slips (2/10), magazine paper (1/10), and manila envelopes (9/10) for subsequent STR profiling. Fingerprints were detected on all paper types. Friction ridge detail quality was not affected by the vacuum collection process. As a result, this small validation study supports that dry vacuuming should be implemented into casework. There is minimal risk of damaging prints in the attempt of collecting DNA.
Hopkins, Christian, "Further evaluation of a dry vacuuming technique for recovery of DNA from handwritten documents" (2020). CUNY Academic Works.