Degradation of Blood Sourced Dna on Knives

Degradation of logical argument Sourced Dna on KnivesPersistence of deoxyribonucleic acid An examination of abjection of occupation sourced desoxyribonucleic acid on knives, by category substances and the rhetorical implicationsA retrospect of relevant and current peer-reviewed literatureContents (Jump to) relative incidence of homicidesKnife discourtesy rhetorical presumptive interrogationsPhenolphthalein and LeucomalachiteFalse positivesLuminolLuminol editionsFalse positives deoxyribonucleic acidqPCRSingleplexMultiplexRFLPSTRsLCN progress techniquesForensic MarkersGeneral Household dry cleanersBl distributivelyes detergentAll-purpose immaculateAnti-Bacterial disinfectantSimilar studiesResearch cast outlineReferencesFiguresFigure 1. Incidence of homicide victims and impeach 2003-2013 dining tablesTable 1.Homicide figures and methods of killing from 2003-2013Table 2.Homicide methods in Lothian and Borders 2006-11AbbreviationsCODIS Combined deoxyribonucleic acid index out lineDNA Deoxyribonucleic acidLCN secondary copy topicLMG Leucomalachite chiliadPCR Polymerase range answerqPCR Real time Polymerase cooking stove receptionRFLP Restriction fragment length polymorphisnsSGM Second generation multiplexSTR go around tandem repeatOften later an assault with a weapon, i.e. a stabbing or murder, renders are made to clean and or dismiss of the weapon utilise. The approximately readily available weapon is a clapper, whether the round off is pre-planned or spur of the moment, knifes are easily available to barter for and are as well, let on and parcel with every dwelling house i.e. kitchen.Incidence of homicidesIncidences of homicide in Scotland are at the low-downest point for ten eld, having dropped from 109 in 2003 to 62 in 2013, as seen in Figure 1.Fig 1. Incidence of homicide victims and acc utilize 2003-2013 (ScotGov, 2013)Table 1. Homicide figures and methods of killing from 2003-2013 (ScotGov, 2013)Table 1 shows that homi cide using a incisive instrument is the most coarse method, at the highest point in 2010-11 was 61% and at the lowest point in 2005-06 was 35.79%.Knife wickednessTable 2 shows that more than half (58.2%) of the murders committed in Lothian and borders between 2006 and 2011 used a kitchen knife.Table 2. Homicide methods in Lothian and Borders 2006-11, Adapted from (Kidd, Hughes and Crichton, 2013)Forensic presumptive testsForensic presumptive tests hindquarters be used at scenes of crimes for various reasons. They can test to see what a substance might be i.e. drugs, blood. thither are various reagents available for use in the presumptive testing for the presence of blood at a crime scene, using wide-ranging types of reactions.Phenolphthalein and LeucomalachitePhenolphthalein is the main reagent used in the Kastle-Meyer presumptive test for blood. This test is primarily used one unidentifiable stains, therefore this is used upon visible (patent) samples.The Kastle-Meyer test is a catalytic method, the phenolphthalein will cause an alkaline solution to pass pink after its oxidation by peroxide when blood is present. concord to (Johnston et al., 2008), it will detect blood as dilute as 1 part in 10,000.False positivesThere are several counterfeit positives for the test and these include harmonize to (Virkler and Lednev, 2009) chemical oxidants and fruit and may withal include vegetable peroxidases.(Garofano et al., 2006), show that the Kastle-Meyer, Phenolphthalein, test is not as clear to blood as Luminol, which is stated as detectable to 1 part in 10,000,000.Leucomalachite Green or LMG is another widely used catalytic method to presumptive test for blood. It works by the same regulation as Kastle-Meyer with the exception of the stain universe gently rubbed with filter piece of music directing the reagent. After no colour has developed hydrogen peroxide is again added as in Kastle-Meyer and a green colour change in this case is in indicative of th e presence of Blood. Johnston et al, also state that Leucomalachite green has a sensitivity similar to that of Phenolphthalein, 1 part in 10,000.LuminolLuminol is a forensic presumptive test for latent blood, i.e. blood which cannot be seen. aversion scenes are often cleaned afterwards by the perpetrator in an attempt to hide any(prenominal) evidence of what had occurred. Luminol allows crime scene investigators to see the teeming picture at a cleaned crime scene.Webb et al, 2006, State that Luminol is known as the most sensitive of the presumptive tests currently used at crime scenes.Luminol variationsAccording to (Patel and Hopwood, 2013) There are two more commonly used Luminol formulations. These formulations were developed by Grodsky in 1951, Luminol I, and weber in 1961, Luminol II.Luminol I or the Grodsky formulation uses a tooshie of sodium carbonate and sodium perborate as the oxidising agent. However Luminol II or the Weber formulation uses a base of sodium hydroxide a nd hydrogen peroxide as its oxidising agent.Commercial luminol products work become more readily available in the recent years and brands such as BlueStar and BlueStar Magnum and Lumiscene, have come onto the market. These products offer the advantage of being easier to prepare than the more traditional formulations.However according to (Quinones et al., 2007) The Grodsky formulation of Luminol I can have a detrimental lay out on the power to subsequently perform DNA analytic thinking in comparison to the Weber and BlueStar alternatives.False positivesLuminols sensitivity may be an advantage at finding the smallest drop of blood, but it is also its downfall.DNADNA is without incertitude the greatest scientific discovery of forensic use to date.PCRAkane et al., 1994 investigated the role haemitin from blood played in interfering with DNA and in inhibiting the polymerase chain reaction. This early study suggested that a haem-blood protein complex caused inhibition issues to the po lymerase chain reaction and forwarded the investigations into a more reliable PCR technique.qPCRqPCR or real time polymerase chain reaction,RFLPRFLP or Restriction Fragment Length PolymorphismsSTRsSTRs or Short tandem repeats, are genetic markers which were first discovered in the early 1990s. (Edwards et al., 1992) Showed that STRs were an good tool when used for human identity testing. They showed that there were enough variation through alleles for individuals to be positively identified.STR profile works by canvass sizes of the sample DNA STRs with standardized databased allelic ladders.New alleles are tranquilize being discovered with variations in size which may not be found in commercially available ladders.LCN(Gill et al., 2000) explain that LCN or low copy number, in a PCR amplification technique which can be applied to DNA samples with as little as Kloosterman Kersbergen, 2003, explain that 28 + 6 improved efficacy of DNA sample genotyping. Their 34 cycles/second PCR technique instead of the normal 28 PCR cycles offered an alternative approach to genotyping forensic DNA samples, which are perhaps low woodland or degraded.Low copy number analysis of DNA is not without problems. The most common issues with LCN are allelic drop-out, heterozygote imbalance, stutter peaks/products and unexpected allelic peaks.Allelic drop-out falter productsForensic MarkersIn the US a system known as CODIS is used for DNA profiling. CODIS uses 13 loci and Amelogenin. The loci used are CSF1PO, FGA, TH01, TPOX, VWA, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, and D21S11.The DNA profiling system used in the UK is SGM Plus (SGM+). This system looks at 11 different loci on different chromosomes (independent inheritance) with a large number of alleles. As well as looking at Amelogenin, the sex marker, the SGM+ includes the markers D2S1338 and D19S433 along with octonary CODIS overlapping loci FGA, TH01, VWA, D3S1358, D8S1179, D16S539, D18S51, and D21S11. (Cotton et al., 2000) Validated the most recent 11 loci STR DNA analysis method for use in standard forensic casework. The technique was also validated for use in casework involving 1ng of DNA, i.e. LCN.HUMVWFA31/A (vWA)HUMTHO1 (THO1)HUMFIBRA (FGA)General Household CleanersIf you have committed a crime, disposing or destroying of the evidence is more than presumable your next step. More often than not this is problem faced by forensic scientists, that a deliberate attempt to remove any of the biologic material i.e. evidence, blood, using a variety of cleaning materials. Most lot store their cleaning supplies in their kitchen or bathroom, so general household cleaners are to be examined.Every household will contain basic cleaning materials such as decolorizees, detergents, disinfectants and perhaps multi-cleaners. Cleaning materials not only have the ability to potentially cause contamination to of any of the surviving evidence but also to degrade any DNA which may still be pres ent on the evidence. Degradation of the DNA will make it difficult to produce and gain a profile which could be used to link the weapon to the crime.BleachesBleaches can cause some problems at crime scenes, thanks to the American television show iniquity Scene Investigation (CSI Las Vegas) most people will know that bleach renders the forensic presumptive blood tests pretty much useless. According to (Harris et al., 2006), by of all the cleaning products on the market bleach also has the most harmful effect on the quality of DNA available to triumph a profile. They also state that bleach seemed to cause continued degradation of the DNA over time. Common brands of household bleaches include Domestos, Harpic, Mr Muscle, Cif and Supermarket own brands. detergentCommon brands of household detergents include Fairy, Imperial leather, Carex, Daz and Bold.Anti-Bacterial disinfectantCommon brands of household anti-bacterial disinfectant include Dettol, Savlon, TCP and supermarket own bra nds.Similar studiesResearch project outlineThis study aims to investigate whether the knife substrate has any effect on the quantity of DNA retained on the weapon after an assault whether deliberate attempts to remove any biological material, using a variety of household cleaning materials, affect the quality and quantity of DNA that is recoverable and if DNA is recovered from a weapon, whether it was signly detected by presumptive blood tests.The knife substrates used here were, 18 Kitchen knife and 20 Serrated kitchen knife.The household cleaning materials were as follows, Bleach (Domestos), Detergent (Fairy) and Anti-Bacterial disinfectant (Dettol).Blood samples are to be applied to the blade of each knife, it should be allowed to air dry and then cleaned until no blood or residues thereof are visible. Each knife should then again be allowed to air dry and be mopbed using a double swab technique.Each cleaning material is applied to the two different knife substrates and the pair s are numbered 3-18, with knife set 1 2 being control, the initial DNA for comparison should be swabbed before the control knifes are dry and washed with warm water only. Cleaning materials should be used according to the manufacturers guidelines.PCR will be performed on the extracted samples usingThe control samples will be used to examine which was the largest contributing factor in compromising the quality and/or quantity of the sample gained.ReferencesThe Scottish Government, (2013) Statistical Bulletin, Homicide in Scotland 2012-13, Online procurable https//alpha.scotland.gov.uk/government/uploads/system/uploads/attachment_data/file/417/Homicide_in_Scotland_2012-13_statistical_bulletin.pdf Accessed 02/10/2014Cotton, E. A., Allsop, R. F., Guest, J. L., Frazier, R. R., Koumi, P., Callow, I. P., Seager, A., and Sparkes, R. L. (2000) Validation of the AMPFlSTR SGM plus system for use in forensic casework. Forensic Sci Int. Vol.112(2-3), pp.151-61.Edwards, A., Hammond, H. A., Jin , L., Caskey, C. T., and Chakraborty, R. (1992) Genetic variation at five trimeric and tetrameric tandem repeat loci in four human commonwealth groups. Genomics. Vol.12(2), pp.241-53.Garofano, L., Pizzamiglio, M., Marino, A., Brighenti, A., and Romani, F. (2006) A comparative study of the sensitivity and specifity of luminal and fluorescein on diluted and aged bloodstains and subsequent STRs typing. International intercourse Series. Vol.1288(0), pp.657-659.Gill, P., Whitaker, J., Flaxman, C., Brown, N., and Buckleton, J. (2000) An investigation of the austereness of interpretation rules for STRs derived from less than 100 pg of DNA. Forensic Sci Int. Vol.112(1), pp.17-40.Harris, K. A., Thacker, C. R., Ballard, D., and Court, D. S. (2006) The effect of cleaning agents on the DNA analysis of blood stains deposited on different substrates. International Congress Series. Vol.1288(0), pp.589-591.Johnston, E., Ames, C. E., Dagnall, K. E., Foster, J., and Daniel, B. E. (2008) Comparison of presumptive blood test kits including hexagon OBTI. J Forensic Sci. Vol.53(3), pp.687-9.Kidd, S., Hughes, N., and Crichton, J. (2013) Kitchen knives and homicide A systematic study of people charged with murder in the Lothian and Borders character of Scotland. Med Sci Law. Vol.54(3), pp.167-173.Patel, G., and Hopwood, A. (2013) An evaluation of luminol formulations and their effect on DNA profiling. Int J Legal Med. Vol.127(4), pp.723-9.Quinones, I., Sheppard, D., Harbison, S., and Elliot, D. (2007) comparative degree Analysis of Luminol Formulations. Canadian Society of Forensic Science Journal. Vol.40(2), pp.53-63.Virkler, K., and Lednev, I. K. (2009) Analysis of personify fluids for forensic purposes From laboratory testing to non-destructive rapid confirmatory identification at a crime scene. Forensic Science International. Vol.188(13), pp.1-17.