Home Forums Discussion Just how fallible is forensic DNA?

This topic contains 314 replies, has 2 voices, and was last updated by  Alfredanige 12 hours, 28 minutes ago.

Viewing 15 posts - 1 through 15 (of 315 total)

Just how fallible is forensic DNA?

  • jeeg

    Is DNA evidence foolproof?

    Reply
    jeeg

    Although DNA detection might have advantages over fingerprint dusting, the test is nevertheless fallible. Environmental factors at the crime scene such as heat, sunlight, or bacteria can corrupt any genetic data. Any DNA evidence must be stored in sterile and temperature controlled conditions. Criminals have been suspected of contaminating samples by swapping saliva.There is room for human error or fraud in comparing samples taken from suspects with those removed from a crime scene. The accuracy of any genetic profile is dependent upon the number of genes examined. Where less than four or five genes can be investigated, the PCR technique serves only to exaggerate any defects or omissions in the sample. In 1995 an 18 month investigation was launched into allegations that the FBI Crime Lab was ‘drylabbing’ or faking results of DNA comparisons.Even a complete DNA profile cannot indicate the length of time a suspect was present at a crime scene or the date in question. The mere creation of a database cannot be the panacea for crime detection.

    Reply
    Jose
    Jose

    For all the case-solved moments it provides on television crime dramas, DNA is far from a perfect forensic tool.

    Samples can degrade over time, confounding analysis. The handful of gene markers used by crime labs to identify individuals aren’t quite so unique as expected.

    Reply
    Sanjay
    Sanjay

    Another problem with courtroom DNA is the “CSI effect”: when crime lab analysts know a sample comes from a prime suspect, they’re more likely to make a match.

    Reply
    PopGen
    PopGen

    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0034267#pone-0034267-t001

    Cryptic Distant Relatives Are Common in Both Isolated and Cosmopolitan Genetic Samples

    Although a few hundred single nucleotide polymorphisms (SNPs) suffice to infer close familial relationships, high density genome-wide SNP data make possible the inference of more distant relationships such as 2nd to 9th cousinships. In order to characterize the relationship between genetic similarity and degree of kinship given a timeframe of 100–300 years, we analyzed the sharing of DNA inferred to be identical by descent (IBD) in a subset of individuals from the 23andMe customer database (n = 22,757) and from the Human Genome Diversity Panel (HGDP-CEPH, n = 952). With data from 121 populations, we show that the average amount of DNA shared IBD in most ethnolinguistically-defined populations, for example Native American groups, Finns and Ashkenazi Jews, differs from continentally-defined populations by several orders of magnitude. Via extensive pedigree-based simulations, we determined bounds for predicted degrees of relationship given the amount of genomic IBD sharing in both endogamous and ‘unrelated’ population samples. Using these bounds as a guide, we detected tens of thousands of 2nd to 9th degree cousin pairs within a heterogenous set of 5,000 Europeans. The ubiquity of distant relatives, detected via IBD segments, in both ethnolinguistic populations and in large ‘unrelated’ populations samples has important implications for genetic genealogy, forensics and genotype/phenotype mapping studies.

    Reply
    PopGen
    PopGen

    The point of the article above is that in certain populations the likelihood of cryptic or distant relatedness is much higher. Therefore, false positive identifications of crime suspects could be higher.

    Reply
    Mark
    Mark

    A clerical error at the Las Vegas police forensics lab led to a man being jailed for a year for sex crimes he did not commit.

    Lazaro Sotolusson was scheduled to be tried in two sexual assaults involving juvenile victims. Seemingly conclusive DNA evidence formed the heart of the prosecution’s case, and Sotolusson faced multiple life terms if convicted.

    But prosecutors had to dismiss the charges after the police lab acknowldged it had accidentally placed Sotolusson’s name on another man’s DNA sample.

    Reply
    Naveen
    Naveen

    The UK Home Office confirmed its database contains more than 500,000 false or wrongly recorded names. Thats a shocking lapse!

    Reply
    Robert
    Robert

    Look at the Shopian murders of Asiya Jan and Neelofar and how poorly handled DNA evidence was. DNA evidence can do far more harm then good when law enforcement doesnt have the capability of handling it properly-mistakes and even intentional mishanding can become common.

    Reply
    John
    John

    Not to mention the Boston forensic scientist who altered samples to up their conviction rates. Wheres the oversight of labs and personnel??

    Reply
    Marshall
    Marshall

    Two words-human error

    Reply
    Shobita
    Shobita

    Leaving human error aside, the technology itself is exaggerated, bigger databases will necessarily result in more false matches-thats basic math.

    Reply
    William
    William

    I doubt any technology is foolproof, weve only just beguin to learn about genetics, who know what we might learn?

    Reply
    Vandana
    Vandana

    Police in many countries are poorly equipped to properly deal with DNA evidence, even in wealthy countries police have made well documented mistakes. The scale of collection of DNA that we are moving towards far exceeds our capacity to properly harness it without prejudice and error.

    Reply
    Isaac
    Isaac

    What about on site Rapid DNA that they’ll be rolling out soon. Police doing all the analyses on site without lab professionals. How could that go wrong??

    Reply
Viewing 15 posts - 1 through 15 (of 315 total)
Reply To: Just how fallible is forensic DNA?
Your information:




© 2014 Forensic Genetics Policy Initiative