Forensic Science

'Forensic Science' also known as criminalistics, is a branch of science applied in investigations by court or law. The discovery of DNA, in 1986, by Allec Jeffreys, was a major step towards the development of forensic science.

LOCARD'S EXCHANGE PRINCIPLE

Edmond Locard, a French criminologist, later known as the French Sherlock Holmes is now known as the father of modern forensic science.

While studying medicine, he was keen to apply science in legal matters. He wrote his thesis on legal matters, with upto 40 writings, the most well-known is his seven-volume series, Traité de Criminalistique or Treaty of Criminalistics.

He later went on to study alongside Alphonse Bertillon, an anthropologist and later worked with the FSS (French Secret Service) where he could identify the cause, locations and other details of death while examining blood stains.

Through his experience, he formulated a principle that expresses,

“Every contact leaves a trace”.

This is called the Locard's exchange principle, it simply means that a criminal will get something into a crime scene and go taking something from it. This has formed an important basis in the history of how forensic science developed.

TECHNOLOGIES USED

Below are some of the interesting technologies used in Criminalistics

1. LA-ICP-MS (Laser Ablation- Inductively Coupled Plasma – Mass Spectrometry)

If a crime scene involved broken glasses, putting together even the smallest of pieces can give breakthrough clues including bullet directions, weapons used, impact, etc. This machine breaks glass specimen to its atomic structures, aiding forensic scientists in matching glass pieces found.

2. Video Spectral Comparator 2000

With this machine, investigators and scientists can define a piece of paper with its hidden writings, quality, origin, etc even if the paper was damaged by water or fire

3. Forensic Carbon 14 Dating

Commonly used to identify age of anthropological and archeological remains, it is now used even in the field of forensic sciences. This technique involves the calculation of increase or decrease in radioactive carbon.

4. DNA Sequencer

Scientists and lad technicians use evidence like skin, hair or nail samples to identify criminal collecting information of their DNA nucleobases. Incase the samples are highly degraded, a more powerful sequencer is used, which allows them to analyze old bones and teeth.

5. Automated Fingerprint Identification (AFIS) and Magnetic fingerprinting

Helps identify and compare fingerprints at a crime scene which is matched with those in a database. Investigators can get a perfect impressions without contamination with the incorporation of dust and no touch wanding techniques.

LIMITATIONS

Though many technologies have been a breakthrough in this field, there are still limitations that have to be looked upon.

Unreliability of forensic disciplines- Many studies have proved that some methods cannot be reliable completely and requires more investigations and care before coming into a conclusion. For example, 3D Forensic Facial Reconstruction and the bitemark comparison.

Further, validation of methods is equally important. Some of the methods may be capable to produce accurate results however, this accuracy is not validated by sufficient research. For example shoeprint tracing.

Methods that require manual labour may result in unavoidable mistakes by practitioners. Mixing up of samples, contamination of evidences, ignorance of specimens, etc.

7 S’s of Crime Scene Investigation or CSI

Secure the scene: This includes minimum movement into and out of the scene to preserve possible evidences.

Separating witnesses: Witnesses must be found and made sure they do not communicate and create a story. Contact details must be taken to ensure their availability for investigations

Scan the scene: This involves deciding on what and where pictures must be taken

See the scene: Pictures are taken by the photography unit of the forensic team

Sketching the scene: Marking the cardinal directions and sketching the possible scene

Search for evidence: Trying to find evidence and marking them

Securing and collecting evidence: Using proper materials and tools to avoid contamination and loss of evidence.