NCJ Number
199424
Journal
Crime & Justice International Volume: 19 Issue: 70 Dated: February 2003 Pages: 31-32
Date Published
February 2003
Length
2 pages
Annotation
This article discusses the nature and investigative prospects of a new technique in DNA analysis called Low Copy Number (LCN) DNA, which claims to provide unprecedented levels of detection.
Abstract
Whereas traditional DNA evidence comes from blood, semen, or hair samples, LCN DNA or "trace DNA" can be obtained from as little as a fingerprint or residue from the lip of a drinking glass. In contrast to current methods, LCN DNA involves increasing the number of PCR cycles from 28 to 34. This increase of DNA allows researchers to determine DNA profiles from previously unusable sources. In 1999, the Forensic Science Service (FSS) in England began using LCN DNA casework. The increased sensitivity of LCN methods allowed researchers with the FSS to determine DNA profiles from objects that were simply touched by the suspect. Some complications and limitations of LCN DNA analysis were identified, however. Certain chemicals for latent print identification were found to prohibit subsequent LCN analysis from latent fingerprints. Further, an experiment conducted by the FSS found that DNA detectable by LCN DNA analysis could by transferred from one person to another (e.g., through a handshake) and then to an object. This calls into question the reliability of placing a person at a crime scene through LCN DNA analysis. In 2001, researchers at the laboratory division of the FBI issued a paper that listed some considerations in the use of LCN DNA. One of the primary concerns is the risk of contamination created by increasing the number of PCR cycles from 28 to 34. As the size of the original sample gets smaller, any contamination present will have a larger effect on the results of the analysis. Another concern of the FBI is that any casual contact between a suspect and a victim prior to a crime could lead to the transfer of LCN DNA; current research has not yet determined how long this DNA could remain. Further, with LCN DNA, the sample size is so small that there is not enough left after testing to obtain an independent source to evaluate the data. This makes thorough peer review of laboratories impossible. Further development of LCN DNA and more research into the complicating factors associated with it are required before it will gain widespread use. 5 references