The Inappropriate Collection of Forensic evidence - What could happen in a case when evidence in inappropriately collected

COLLECTION OF FORENSIC EVIDENCE

In the past decade , forensic science has been recognized as a powerful field due to its significance as supporting evidence in criminal cases The development of techniques in handling and analysis of deoxyribonucleic acid (DNA ) samples has influenced police investigators to rely on any information forensic science can offer . The combination of DNA analysis with the study of surrounding insects (entomology ) and pollen (palynology ) has resulted in an efficient and effective method in investigating criminal cases (Leclair et al , 2004 . The inclusion of forensic data in criminal

investigations has thus transformed the process of conviction and to a certain extent , has overturned particular verdicts upon review of old cases . Unfortunately , the convicted individual of those old cases are usually sentenced to death and the DNA evidence is too late to overturn the sentence because the convict is already dead

Forensic DNA analysis currently employs the polymerase chain reaction which is an enzymatic amplification of specific DNA sequences of a particular DNA sample , be it the victim , the suspect or any other individual in the crime scene , through a series of varying temperatures in to generate sample-specific DNA patterns that are visualized on an electrophoretic gel . The specific DNA sequences employed in forensic DNA analysis are known as short tandem repeats (STRs , which are present across the entire genome of each individual . The power of STR analysis is based on the premise that each individual carries a unique STR pattern that can distinguish one person from another , just the same as how fingerprinting works . Forensic DNA analysis is more reliable than fingerprinting because DNA can never be erased or changed , unlike fingerprints which could be removed when the fingers of a suspect are burned or are covered by gloves , resulting in fingerprint-free hands The principle of STR analysis comes from the concept that these DNA sequences have a unique number of copies in each individual and the probability of having two individuals having the same number of copies geometrically decreases as more DNA locations or loci are analyzed

Results from the STR analysis of forensic DNA samples may show either the same or different DNA pro between the suspect 's actual DNA and the DNA collected from the crime scene . If the results show a different DNA pro , then the suspect can be indicted from the criminal investigation . However , if the DNA pro from the STR analysis is not different , the suspect can not be convicted immediately . The forensic scientist must then compute for the probability that an individual picked out through a random process would general an identical pro as that employed in the STR analysis . The principle of population genetics is the core behind this computation , which involves a combination of statistics , mathematics , genetics and biology . The Hardy-Weinberg Law of equilibrium is applied to cases that show positive results in the STR analysis , which determines that chances that an individual selected at random would have a similar DNA pro with those STR sequences that...