The Use of Biochemistry in Forensic Science Essay

Biochemistry is of great public-service corporation for Forensic Science probes, with the biochemical technique of DNA fingerprinting being of peculiar importance. The development of the biochemical techniques for Deoxyribonucleic acid sequencing allowed the genomes of beings to be sequenced ( Berg et al, 2002: Preliminary ) . As a consequence, familial markers can now be used to place single members of a population ( James and Nordby, 2005: 283 ) . This capacity is clearly good in forensic probes. However, despite their public-service corporation, biochemical techniques must be applied with cautiousness in forensic scientific discipline. The consequences of biochemical techniques used in forensic scientific discipline can hold serious deductions for the lives of persons.

I will show both the value and restrictions of utilizing biochemistry in forensic scientific discipline through concentrating upon the usage of Low Copy Number ( LCN ) Deoxyribonucleic acid typing in forensic scientific discipline.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!

order now

LCN DNA profiling


The development of LCN DNA profiling provided forensic scientists with the capacity to analyze infinitesimal measures of DNA. The technique is sensitive plenty to analyze “ merely a few cells ” ( Gill, 2001: 229 ) . This technique is hence of peculiar benefit when look intoing serious offenses for which there is limited grounds available ( FSS, 2005a: no folio ) . An illustration is provided by the forensic probe which followed the 2001 slaying of Peter Falconio in Australia.

The grounds base was badly limited as no organic structure was found. However, really little measures of DNA were discovered inside the manus ties which had been used during the onslaught and on the gear stick of the victim ‘s new wave ( FSS, 2005: no folio ) . The usage of LCN DNA profiling enabled this grounds to be linked to Murdoch, who was already suspected of the slaying ( FSS, 2005: no folio ) .LCN DNA analysis was besides important in work outing a documented slaying in Northern Italy. Although no hint grounds was discovered on the victim ‘s organic structure or at the scene of the offense, a hunt of the victim ‘s auto provided blood discolorations, perspiration and tegument samples. The little sums of Deoxyribonucleic acid yielded by these samples provided profiles which were “ indistinguishable to that of the spit obtained from the suspect ” ( Pizzamiglio et al, 2004: 437 ) . When confronted with this grounds, the suspect confessed the offense ( Ibid.

) .

The biochemical technique

The increased sensitiveness of the LCN technique is achieved by increasing the figure of polymerase concatenation reaction ( PCR ) elaboration rhythms used ( Gill, 2001: 229 ) . Although optimal efficiency is attained by utilizing no more than 28-30 PCR elaboration rhythms ( Ibid. ) , a assortment of surveies have yielded utile consequences utilizing more rhythms. Findlay et Al ( 1997 ) obtained profiles from individual cells by utilizing 34 rhythms ; Wiegand et Al ( 2000 ) analysed epithelial cells which had been transferred from the attacker during choking utilizing 31 rhythms and Van Hoofstat et Al ( 1998 ) analysed fingerprints from tool clasps by utilizing every bit many as 40 rhythms.The increased sensitiveness offered by this technique is improbably good for forensic scientific discipline probes. The cardinal dogma of forensics is: “ every contact leaves a hint ” ( Locard, 1910 ) . By enabling the analysis of hardly seeable samples, LCN DNA profiling increases the fact-finding power of forensic scientific discipline ( Hoffman Wulff, 2006: 2 ) .

However, with this increased sensitiveness comes increased hazard of misunderstanding. For illustration, the extremely sensitive technique may uncover Deoxyribonucleic acid from beginnings other than the sample analysed and the consequences must be interpreted with utmost cautiousness ( Gill, 2001: 229 ) . The restrictions of the technique will now be explored in item.

Restrictions of the technique

1. Experimental mistakes

Due to the increased figure of PCR rhythms used for LCN DNA profiling, there is an increased likeliness of experimental mistakes, which may significantly impact the Deoxyribonucleic acid profiles obtained ( Budowle, 2001 ) . These experimental mistakes include: discriminatory elaboration of allelomorphs ( doing allele drop out ) , the visual aspect of false allelomorphs when stammers are preferentially amplified and the discriminatory elaboration of allelomorphs which are present because of taint ( Gill, 2001 ) .

As a consequence of these experimental mistakes, it is hard to formalize the consequences of LCN DNA typewriting ( Budowle et al, 2001: 2 ) . Because experimental mistakes occur indiscriminately, the consequences of LCN DNA profiling are non consistent and replicate analyses can bring forth different DNA typewriting consequences ( Gill, 2001 ) . In add-on, because the established reading thresholds for Deoxyribonucleic acid analysis are excessively big to use to the LCN technique, there is no stochastic threshold for usage when measuring the consequences of LCN processing ( Hoffman Wulff, 2006: 2 ) . Therefore, the figure of allelomorphs required in order to set up similitude is unfastened for argument ( Budowle et al, 2001 ) .

2. Contamination

Alongside consciousness of the possibility for experimental mistakes to cut down the truth of LCN DNA profiling, it is of import to see the impact of evidentiary taint.

There is a high hazard of DNA taint before, during and after the forensic event under consideration, which reduces the truth of the technique. Although there is besides a hazard of taint when set abouting standard DNA analysis, it has less impact upon the consequences of the profiling. As adventitious transportation and taint normally involve merely low degrees of DNA, their consequence upon the profile obtained by standard DNA analysis is minimum ( Gill, 2001: 231 ) . However, in LCN DNA analysis, the low degrees of Deoxyribonucleic acid from taint pose a far more important job.

As the kernel of the technique is the sensing of minute degrees of Deoxyribonucleic acid, there is a far greater likeliness of taint DNA holding a significant consequence upon the profiles obtained. Due to the sensitiveness of the technique, both background degree Deoxyribonucleic acid and Deoxyribonucleic acid from insouciant contact will be detected ( Budowle, 2001: 2 ) . This is most debatable, as these contaminations can non be removed physically or statistically. Because there is no manner that the motions and contacts of the victim before, during and after the offense event can be assessed and accounted for, the possibilities of adventitious transportation can non be straight ascertained ( Gill, 2001: 230 ) .The possibility of secondary transportation ought to besides be acknowledged. Theoretically, secondary transportation means that immaterial DNA could be carried by the culprit and deposited at the offense scene.

Van Oorschot and Jones demonstrated that Deoxyribonucleic acid can be transferred from objects to custodies ( 1997 ) . Although the likeliness of such transportations is contested, such secondary transportations could ensue in the deposition of a multi-source sample at a offense scene ( Phipps and Petricevic, 2007 ; Ladd et Al, 1999 ) . It may be really hard to set up whether a true mixture of DNA profiles exists when utilizing the LCN technique ( Hoffman Wulff, 2006: 2 ) .

Therefore, it is of import to admit that grounds may include a mixture of DNA profiles, which may include disinvolved persons, the culprit and offense scene research workers ( Gill, 2001: 230 ) . Such a possibility greatly complicates reading and means that the consequences obtained could good be flawed. When the consequences provided by the technique may impact the autonomy of an person, it is peculiarly of import that restrictions and possibilities for inaccuracy are acknowledged.Troubles related to taint are made even more important as a consequence of the “ considerable deficiency ” of understanding about the issues of the transportation and continuity of DNA, which constrains scientists ‘ ability to statistically account for DNA taint ( Gill, 2001: 230 ) . There are important differences in DNA deposition between persons and as some are “ better than others at casting Deoxyribonucleic acid ” , disintegrate rates are unpredictable ( Phipps and Petricevic, 2007: 167 ; Lowe et Al, 2002 ) . For illustration, Murray et Al ( 2003: 780 ) found that ‘good ‘ Deoxyribonucleic acid spillers would come to organize the major constituent of the DNA mixture found on a 2nd manus ticker strap after merely several yearss. By contrast, ‘poor ‘ spillers took every bit long as two hebdomads to consist the bulk of the Deoxyribonucleic acid in the mixture ( Ibid. ) .

Similarly, van Oorschot and Jones ( 1997: 767 ) demonstrated that ; when a figure of persons handled objects, the dominant DNA profile was non ever that of the person who last held the object. Rather, the dominant DNA profile was dependent on the casting ability of persons ( new wave Oorschot and Jones, 1997: 767 ) .However, placing persons as being either ‘good ‘ or ‘poor ‘ spillers is non possible, because the casting ability of a given person does non stay consistent.

Indeed, variable factors have been demonstrated to impact the sum of DNA deposition. Phipps and Petricevic ( 2007 ) established that DNA deposition is affected by factors such as whether contact is made by the dominant or non-dominant manus and the clip since the manus was last washed. Therefore, as the transportation and continuity rates of DNA are impossible to set up, LCN DNA profiling can non supply an indicant of when DNA deposition occurred. As such, both consciousness of and farther research into the multiple factors which influence DNA casting is required ( Phipps and Petricevic, 2007 ; Hoffman Wulff, 2006 ) .Further taint can happen during the aggregation of grounds. Forensic grounds is by and large collected in uncontrolled environments, by constabulary officers whose preparation in continuing the unity of biological samples is, at best, limited ( Lynch, 2003: 96 ) .

This factor becomes particularly debatable when utilizing LCN DNA analysis, as the little sample size greatly increases the hazard of taint. Given that LCN DNA analysis ought merely to be undertaken in unfertile environments, where equipment and furniture must be often bleached, the quality of the aggregation of the sample is really of import ( Gill, 2001: 229 ) . Although laboratory criterions can non be expected, the grounds must be reviewed with an recognition of this restriction.In the UK, Regina v. Hoey in 2007 demonstrated the possible impact of these restrictions. The footing for Hoey ‘s 2003 strong belief for 29 slayings during the Omagh bomb onslaughts was the grounds obtained from LCN DNA profiling.

However, the strong belief was so overturned on entreaty in 2007, as the entreaty established that the DNA grounds had been handled in a “ thoughtless and slapdash ” manner ( Weir, 2007: 23 ) . Although this illustration displays that grounds which has been treated falsely may be dismissed at entreaty, it is important to observe that grounds ought to be presented alongside information about the possible restrictions of its truth, as sedate abortions of justness may otherwise consequence.Due to the restrictions of the technique, analysis of the consequences of LCN DNA analysis must merely be done with an consciousness of the “ particular considerations ” about the possible inaccuracy of the technique ( Gill, 2001: 229 ) . It is important that both forensic scientists and courtroom staff are cognizant that LCN DNA grounds is inextricably linked to a higher likeliness of accomplishing adventitious similitudes or exclusions than standard DNA profiling ( Gill, 2001: 230 ) . This is clearly debatable when the consequences of the technique are being used lawfully, as wrong outcomes “ have lay waste toing and indefensible effects ” ( Morgan and Bull, 2007a: 43 ) . Although it may be possible to statistically account for experimental mistakes in the hereafter, it will stay important to admit the potency for forces to do errors. In U.

S. V. Llera-Plaza in 2002, an FBI scientist stated: “ mistake rate is a hard thing to calculateaˆ¦ to state there ‘s an mistake rate that ‘s definable would be a misrepresentationaˆ¦ the method is one thing, people doing errors is another issue ” ( Saks and Koehler, 2005: 894 ) .

3. Problems with reading

Deoxyribonucleic acid profiles ( both normal and LCN ) are frequently non interpreted right. Although DNA grounds ought to merely be used to except, ‘matches ‘ are normally referred to.

For illustration, following the 1981 slaying of Marion Crofts, the UK Forensic Science Service contended that a LCN DNA profile found on the victim ‘s vesture matched that of the fishy Jasinskyj ( FSS, 2005 ) . Similarly, in U.S. v. Byrd, a forensic scientist for Pennsylvania State Police testified that it was 99 % likely that the Deoxyribonucleic acid obtained from the slaying implements matched the Deoxyribonucleic acid of Byrd and his victim ( Hoffman Wulff, 2006 )Despite the fact that DNA analysis superseded techniques such as handwriting analysis and lie-detector trials which were less ‘scientific ‘ , it remains of import to admit the mistakes of reading which may still happen with the newer techniques ( Lynch, 2003 ) . Although the methodological analysis underpinning DNA analysis is scientifically sound and has a “ steadfast theoretical footing ” ( Broeders, 2006: 152 ) , utilizing processs which are “ platitude in biomedical research ” ( Lynch, 2003: 95 ) ; forensic scientific discipline remains an applied scientific discipline. As such, although the consequences of the biological procedure may be sound, the illations made from these consequences could still be wrong.

This consideration is particularly relevant for LCN DNA analysis, where an seemingly ‘matching ‘ profile can be obtained through taint of the grounds.Matchs and categorical designations are impossible throughout the kingdom of forensic probe, “ unless the figure of possible beginnings is limited and known ” , ( Broeders, 2006: 153 ) . Although the chance of persons exhibiting high degrees of DNA similarities is considered to be “ vanishingly little ” ( Broeders, 2006: 155 ) , DNA features are nevertheless category features and therefore can non individualize ( Thornton and Peterson, 2002 ) . Merely where mention to “ an indefinitely big set of alternate possible beginnings ” has been made, can the Huberian rule of individualization be exercised ( Broeders, 2006: 153 ) . This invokes the classical initiation job, that individualization from DNA analysis would necessitate the analysis of everyone who has of all time lived, is populating and will of all time populate. As such, DNA can merely supply a probabilistic decision that the profile matches that of the suspect ( Broeders, 2006 ) . However, correct forensic process would merely of all time assess the similarity of DNA profiles after neglecting to except them ( Budowle et al, 2001 ) .

As Stoney so articulately highlighted, “ what made us of all time think we could individualize utilizing statistics? ” ( 1991: 197 ) .Therefore, utilizing DNA profiling for designation instead than exclusion overlooks the very nature of DNA profiling as a categorization procedure and besides contradicts one of the cardinal dogmas of forensic scientific discipline: “ when set abouting comparing of samples, exclusion should be sought instead than a lucifer ” ( Morgan and Bull, 2007: 86 ) . As a consequence of the increased sensitiveness of LCN DNA analysis and the hazards detailed supra, purely adhering to the rule of exclusion is particularly of import. However, it is apparent that current usage of LCN DNA typewriting does non ever carry through this cardinal doctrine of forensics.The outlook of obtaining DNA ‘matches ‘ has been farther complicated by the CSI consequence, which has led to juries puting increased trust in the ‘expert ‘ informant and contributed to the wrong thought that forensic scientific discipline is infallible ( Morgan and Bull, 2007a ) . Although LCN DNA typing utilizations scientific techniques, in the courtroom credibleness is “ fashioned and undermined in testimony ” ( Lynch, 1998: 829 ) .

As the justice and jury are improbable to be familiar with scientific theory and pattern ( Morgan and Bull, 2007a ) , the jury ‘s position as a “ susceptible organic structure of persons ” , whose judgement may hold been affected by media portraitures of powerful and successful forensic techniques becomes most important ( Morgan and Bull, 2007a: 44 ) . Although tribunals tend to put their trust in the ‘expert ‘ informant ( Lynch, 2003 ) , wrong expert testimony has been cited as a subscriber in 63 % of unlawful strong beliefs ( Saks and Koehler, 2005: 893 ) . Attachment to the exclusionary rule is hence peculiarly of import, particularly due to the sensitiveness of LCN DNA profiling.The CSI consequence has besides increased juridical outlook for grounds to be presented. Juries now frequently “ demand unreasonable degrees of physical grounds ” in order to make a finding of fact ” ( Morgan and Bull, 2007: 84 ) . ‘Negative grounds ‘ adept informants may even be called upon to explicate an absence of grounds in a test ( Hoffman Wulff, 2006 ) .

Indeed, the increased sensitiveness of sensing provided by LCN DNA analysis may move to foster such outlooks. However, it is of import for forensic scientists and courtroom staff to stay aware that contacts that are unrelated to the forensic event may hold transferred plenty Deoxyribonucleic acid to be detected by LCN analysis.

4. The Court

Although DNA profiling utilises scientific techniques and may therefore look to be an nonsubjective process, the grounds itself remains soundless and must be given a voice in the courtroom ( Jasanoff, 2006: 330 ) . As such, the nonsubjective scientific discipline has to be represented. This demand for representation renders the courtroom a “ sociology of cognition machine ” , within which uncertainness can be produced ( Lynch, 1998: 829 ) .

Indeed in 1995, U.S. v. Simpson, saw the suspect being exonerated after his “ star-studded ” legal squad exploited every failing in the procedure of grounds interlingual rendition from offense scene to courtroom. ( Jasanoff, 1998: 715 ) . As there are so many restrictions to see where LCN DNA profiling is used, it is possible for attorneies to utilize strategically deployed linguistic communication and powerful visual images of grounds to dramatically act upon legal proceedings ( Jasanoff, 1998 ) .There is hence a strong statement for controls on grounds unity and adept quality to be implemented, as seen in the U.

S. legal system. Frye v. United States, 1923, constitutes the chief control on grounds in the American tribunals, specifying expertness as: that which has “ gained general credence in the peculiar field in which it belongs ” ( Saks and Koehler, 2005: 894 ) . Regulations such as these are desperately required in the UK, where “ fresh scientific techniques ” are presently accepted, without particular examination ( Ormerod, 2002: 774 ) . It is possibly stating that LCN DNA grounds is considered admissible in UK tests, but used merely as a last resort in a US condemnable instance ( Hoffman Wulff, 2006: 4 ) .


This essay has argued that, although biochemistry is undeniably of great public-service corporation for forensic scientific discipline, the span between a research lab scientific discipline and an applied scientific discipline must be carefully negotiated. This statement has been demonstrated through a focal point upon the restrictions of the usage of LCN DNA profiling. However, although convicting a fishy entirely on the footing of LCN DNA grounds would non be wise, making so would besides belie a cardinal dogma of forensic analysis: the demand “ to use a figure of independent techniques ” ( Morgan and Bull, 2007: 86 ) .

The restrictions of LCN DNA analysis would be greatly reduced in significance if the findings are supported or contradicted by grounds from other techniques, as dictated by the doctrine of forensic scientific discipline. This paper has demonstrated that the restrictions of LCN DNA typing are considerable, nevertheless adhering to the dogmas of forensic probe will intend that these restrictions are extremely likely to go open or negated.


I'm Ruth!

Would you like to get a custom essay? How about receiving a customized one?

Check it out