Contact DNA evidence is becoming a common occurrence at crime scenes and is often collected and analyzed for human identification. Current Short Tandem Repeats (STRs) techniques are still limited in Low Copy Number (LCN) DNA analysis due to contamination and stochastic effect. Increasing DNA yield from the extraction step is a potential benefit for many investigations. One hundred and fifty samples collected from five female individuals on five commonly-used items were extracted by two forensic extraction systems: DNA IQTM and PrepFiler Kit® with subsequent genotyping by PowerPlex® 16 HS system. Results determined that these extraction systems are not suitable for LCN DNA samples. Only two complete STR profiles were produced without contamination. These findings indicated that further improvements are required in order to utilize STR analysis for LCN DNA.
