In this post, we will discuss the basic principles and techniques that is related to forensic science – a branch of science that concerns with the analysis of physical crime evidence. An evidence can be thought of as physical objects or physical measurements. It can be thought of as an application of science to criminal justice, but the boundaries are not so firm. The boundaries are actually quite fuzzy, because many of the concepts and ideas of forensic science can also be used in other areas, in other fields.

Interpretation of evidence

Describe about this **

Reliability of evidence

How and to what extent can the evidence be trusted. For example, something like DNA sample is treated as a very reliable evidence that can be use by the court of law to determine whether a person is guilty or not.

Circumstantial evidence

Indirect evidence that tends to prove a fact by proving other events or circumstances which afford a basis for a reasonable inference of the occurrence of the fact at issue.

Presumption of Innocence – This is the default setting of the english law which indicates that if you are charged or accused of a crime, then by default, the legal system must assume you are innocent until you are proven guilty. This implies that the defense side or your side doesn’t have to prove you innocent, however, the prosecution side has to try to prove you guilty. The main task for the defense side is to continuously seek the lapses or the loopholes and raise reasonable doubt in order to obfuscate the prosecution side to succeed.

Actus Reus and Mens Rea – If someone is tried in the court of law for a criminal offense, then there are two things that needs to be done in order to determine the outcome of the decision:

  • Actus Reus – guilty action (criminal action committed)

  • Mens Rea – guilty mind or the intention (intention to commit a criminal action).

Res ipsa loquitur – Latin word that means that the thing speaks for itself.

Prima facie – based on the first impression; accepted as correct until proved otherwise. In common law jurisdictions, prima facie denotes evidence that, unless rebutted, would be sufficient to prove a particular proposition or fact.

Locard’s Exchange Principle

In the world of forensic science, there is a general principle stated by Dr. Edmond Locard (aka the sherlock holmes of france) that whenever two objects come in contact, a transfer of material occurs. This means whenever a potential criminal(s) enters and leaves a crime scene, they will leave something and take something with them.

In short, it gives a powerful basic principle – Every contact leaves a trace.

The principle is Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibres from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.



Some of the popular cases that are worth investigating/analzying are:

Useful Resources

Paper – A Crime Scene Fabricated as Suicide

Paper – When a suicide becomes a forensic enigma: The role of hanging marks and tools of suspension