Cold Crime Investigation Essay
DMitochondrial DNA Examination of Cold Case Crime Scene Hairs http://www.forensicmag.com/article/mitochondrial-dna-examination-cold-case-crime-scene-hairs?page=0,0 By Terry Melton Article Posted: April 01, 2009 Printer Friendly | Forward to a Friend | Share this |
Terry Melton
Forensic mitochondrial DNA analysis of hair shafts and naturally shed hairs is a tool to enhance the investigation of cold cases; this form of evidence historically has had severely limited utility.
Many cold cases have been re-opened in hopes that DNA profiling of evidentiary material may strengthen a case against an existing but weak suspect or identify new leads and new suspects. “Cold hits” are made when nuclear DNA (STR) profiles of semen, blood, or saliva …show more content…
While nuclear DNA is present in only two copies per cell, the small circular mitochondrial DNA molecule (Figure 1) is present in hundreds to thousands of copies per cell and is therefore a naturally abundant DNA molecule. During the 1990s, forensic scientists learned that while naturally shed human hair roots and hair fragments lacking any root at all do not contain sufficient nuclear DNA for routine STR typing, they contain abundant mitochondrial DNA (Figure 2). Today, the ability to perform mtDNA analysis on virtually any head or body hair is a bonus technique in the investigation of criminal …show more content…
Until 1996, when the FBI started using mitochondrial DNA analysis, the only science routinely being applied to shed hairs was descriptive microscopy, a descriptive science prone to bias. While microscopy still has a valuable role to play in the evaluation of questioned hair evidence, it should no longer be used without confirmatory mtDNA analysis. Candidate hairs can be of any age and size and do not need any root material. In most cases when a match is obtained it is possible to eliminate well over 99% of the general population as contributors of a specific hair, with the exception of maternal relatives. With the availability of mitochondrial DNA analysis of questioned hair evidence, cold cases may be re-opened with the knowledge that a validated scientific process can be applied to valuable forensic evidence of previously limited value.
Additional Reading * Holland M Mand Parsons TJ (1999) Mitochondrial DNA sequence analysis: Validation and use for forensic casework. Forensic Science Reviews 11:21-50. * Isenberg AR and Moore JM (1999) Mitochondrial DNA analysis at the FBI Laboratory. Forensic Science Communications 1(2),
Terry Melton
Forensic mitochondrial DNA analysis of hair shafts and naturally shed hairs is a tool to enhance the investigation of cold cases; this form of evidence historically has had severely limited utility.
Many cold cases have been re-opened in hopes that DNA profiling of evidentiary material may strengthen a case against an existing but weak suspect or identify new leads and new suspects. “Cold hits” are made when nuclear DNA (STR) profiles of semen, blood, or saliva …show more content…
While nuclear DNA is present in only two copies per cell, the small circular mitochondrial DNA molecule (Figure 1) is present in hundreds to thousands of copies per cell and is therefore a naturally abundant DNA molecule. During the 1990s, forensic scientists learned that while naturally shed human hair roots and hair fragments lacking any root at all do not contain sufficient nuclear DNA for routine STR typing, they contain abundant mitochondrial DNA (Figure 2). Today, the ability to perform mtDNA analysis on virtually any head or body hair is a bonus technique in the investigation of criminal …show more content…
Until 1996, when the FBI started using mitochondrial DNA analysis, the only science routinely being applied to shed hairs was descriptive microscopy, a descriptive science prone to bias. While microscopy still has a valuable role to play in the evaluation of questioned hair evidence, it should no longer be used without confirmatory mtDNA analysis. Candidate hairs can be of any age and size and do not need any root material. In most cases when a match is obtained it is possible to eliminate well over 99% of the general population as contributors of a specific hair, with the exception of maternal relatives. With the availability of mitochondrial DNA analysis of questioned hair evidence, cold cases may be re-opened with the knowledge that a validated scientific process can be applied to valuable forensic evidence of previously limited value.
Additional Reading * Holland M Mand Parsons TJ (1999) Mitochondrial DNA sequence analysis: Validation and use for forensic casework. Forensic Science Reviews 11:21-50. * Isenberg AR and Moore JM (1999) Mitochondrial DNA analysis at the FBI Laboratory. Forensic Science Communications 1(2),