There has been a huge hue and cry about forensic science in the recent years. Prime time shows are focusing greatly on forensic science and crime investigation. The etymology of the term forensic science goes back to the two Latin words, forensis which means investigations and discussions done in public while science refers to a systematic method of acquiring knowledge. Forensic science has many areas of specialization, like:
Forensic science and DNA testing play a major role in criminal investigations. While forensic toxicology can help to determine the cause of the crime during crime investigation, criminal psychology analyses the mindset of the criminal and can stop future crime from taking place.
Stages of crime investigation
A crime investigation is a systematic process. It takes place over a long period of time and involves some meticulous stages. These stages are ratified universally while investigating a crime scene and needs to be performed systematically and objectively:
A pre-arrest investigation: after the committing of a suspicious criminal act, a preliminary investigation is done to identify the prospective suspect who is to be arrested for further investigation. During this stage the forensic department collects evidences that helps to identify the criminal. A prosecuting attorney decides what charges to file against the suspect.
Arrest: based on the charges, the suspect is arrested and the accused is taken into custody by enforcement of the law. The law enforcement officer can arrest the suspect immediately if any threat is perceived or can come back with an arrest warrant after an initial stage of investigation.
First appearance: after the arrest is done, by law the accused has to be produced in front of the court. During the first appearance the court makes the charges against the accused clear to him or her and also advices the accused to hire a legal counsel.
These are three most crucial stages of criminal investigation followed by a series of hearings in front of the jury where the evidences are produced till the final verdict of the court is delivered.
DNA in forensic technology
There are some biological materials that are used to determine the DNA profile. These include saliva, semen, blood, sweat, bone, teeth, tissue, hair and cells. Investigators investigating a crime scene collect items that may have been used or worn by people involved in the crime scene. From these objects the investigators try to determine the DNA profile and then match it to the person who is their primary suspect.
There are different types of DNA analysis:
Polymerase Chain Reaction (PCR) Analysis: the PCAR analysis produces millions of precise DNA replications even from the smallest cell. Hence it has the advantage of analyzing even the miniscule sample that is gathered from the crime site.
Restriction Fragment Length Polymorphism (RFLP): this was one the first techniques of DNA analysis in forensic science but is slowly becoming obsolete. This technique is becoming obsolete because large size of samples are needed as compared to other techniques.
Short Tandem Repeat (STR) Analysis: this technique analyses individual areas of the DNA. In criminal investigation thirteen areas are analyzed to establish DNA profiles.
Mitochondrial DNA Analysis: this technique is used for samples on which the STR or RFLP techniques fail. There are two types of DNA mitochondrial and nuclear DNA. In all the types of DNA testing the nuclear DNA is removed from the sample, but in this analysis the mitochondrial DNA is removed from the sample.
Y-Chromosome Analysis: the Y chromosome passes from the father to the son and this analysis is used to determine parental disputes.