In September 1996,a new evidence tool was used for the - PDF document

6GenePrintª 1998In September 1996,a n
6GenePrintª 1998In September 1996,a new evidence tool was used for the Þrst time in a United States courtroom.Mitochondrial DNA (mtDNA) evidence was introduced in a Tennessee murderprosecution against twenty-seven-year-old Paul Ware.Without the mtDNA results there wasonly circumstantial evidence pointing to Ware as the suspect in the rape and murder ofa four-year-old girl.The defense claimed that another man in the home,the babysitter,had framedWare,who was found drunk and asleep next to the body ofthe child.SigniÞcantly,the little girl's blood was not found on the suspect,nor was his semen foundWarecase in Tennessee in1996 was the Þrst case in theUnited States where mitochondrialDNAevidence was introduced attrial.Councilin South Carolinahas successfully followed the admissibility ofthis type ofDNAevidence in the U.S.courts.7GenePrintª 1998The amount ofmtDNA isolated fromsuch specimens may be very small,so DNAextraction is followed by PCR ampliÞcation,a process that allows the production ofmanycopies ofthe region ofmtDNA ofinterest.During the PCR process,speciÞc hypervari-able regions ofthe mitochondrial genomeare ampliÞed.There is little legal disputeabout the accuracy ofthe PCR process as itrelates to the validity ofmtDNA typing.After ampliÞcation is complete,themtDNA is sequenced using conventional,widely accepted sequencing methods.Thesequences ofmtDNA isolated from eviden-tiary and known samples are then compared.The sequencing method used for mtDNAtyping is the same as that developed byFrederick Sanger (1),for which he won aNobel Prize.This technique is currently usedin hundreds oflaboratories throughout theworld.The involvement ofthe FBI laboratorywith research in mtDNA began in 1990 whena feasibility study was performed to deter-mine whether mtDNA analysis would beuseful for forensic applications.In 1995,theFBI Crime Lab,under the direction ofMarkR.Wilson and Joseph A.DiZi

nno,conductedand published a validation
nno,conductedand published a validation study (2).As isthe case with traditional DNA typing meth-ods,the validation study is important forforensic purposes Ð enabling prosecutors toshow judges and juries that,no matter howthe DNA has been degraded,that exposuredoes not affect its genetic integrity.In June1996,the FBI Crime Lab ran its Þrst case foruse at trial Ð the WarePEER-REVIEWED PAPERS REGARDING THEMitochondrial DNA has been studiedextensively.There are more than 600 papersin the FBI's research database regarding theforensic utility ofmtDNA.A detailed bibli-ography can be obtained by writing to theauthor at the District AttorneyÕs OfÞce,600Market Street,Chattanooga,TN 37402,ormay be obtained directly from the Hairs andFibers Unit ofthe FBI Crime Lab.SUMMARYMitochondrial DNA is a tool available incases where DNA is degraded or scarce.Thisincludes samples not traditionally thought ofas available for DNA identiÞcation at trialsuch as bone fragments,teeth,hair and otherbiological trace evidence.The FBI Crime Labis currently the only lab in the United Statespreparing this work for use in the U.S.courtsystem,but State labs will follow in the rela-tively near future as this type ofevidencebecomes widely accepted.Most recently,in Aitken,South Carolina,a capital conviction was returned Ð substantially on mtDNA evidence Ð against a30-year-old defendant whose pubic hair waspresent on the bed sheets ofa 72-year-oldmurder victim.The Warecase in TennesseeCouncilin South Carolina has suc-cessfully followed mtDNA's admissibility inthe U.S.courts.By the end of1997,I expectthis proofto be admitted in more than adozen other jurisdictions throughout theUnited States.1.Sanger,F.,Nicklen,S.,and Coulson,A.R.(1977)Proc.Natl.Acad.Sci.USA,5463.2.Wilson,M.R.et al.Int.J.Leg.Med.CASEREPORTFigure 1.A schematicrepresentation ofthe process ofisolation and ampliÞcation ofthehypervariable regions ofmitochondrial DN