Crime scene preservation


The DNA Project believes that in order for the National DNA Database to be effective, the quality and quantity of DNA samples delivered to the FSL for analysis must be optimised. To this end, it believes that rigorous training needs to be implemented amongst key sectors of the SAPS and community, namely: amongst lower level police officers, emergency services and security services, as well as the general public. All of these sectors need to be able to assist in containing, as opposed to contaminating, a crime scene, thereby enabling trained forensic personnel to collect and retain usable DNA evidence for profiling and subsequent prosecution.

In South Africa, it is of great concern that the first people to arrive at a crime scene are often not qualified to investigate the crime scene. The DNA Project accordingly advocates that the SA public should and must familiarise themselves with the proper procedure when securing a crime scene in order to ensure proper identification, preservation, and collection of biological evidence that could render a criminal’s DNA profile. An Investigating Officer has only one chance to collect proper evidence at a crime scene, and this job is regularly thwarted by the destruction of a crime scene due to the negligence and /or ignorance of all or some of the public, emergency services, private security guards and lower level police officers, who arrive at the crime scene before the Investigating Officer has a chance to uplift evidence.


Evidence not identified at the crime scene loses its value due to degradation and/or destruction caused by factors such as the environment, or contamination of the crime scene. The failure to collect evidence as well as evidence not collected under the correct protocols, may render erroneous results, if in any facts at all!

Whilst it is alarming and horrendous that there exists a need in SA to have to educate people on what to do in the event of a crime, whether they are a victim themselves or come across a crime scene. The following section lays out a few basic principles on what to do in the event that you are either a victim of crime or in the event that you are at the scene of a crime or come across a crime scene before the arrival of the mandated SAPS Investigating Officers.

It is vitally important for the general public, the Emergency Services as well as Private Security Guards to be aware of what should and should not be done in these circumstances as well as ensure that people in the immediate area adhere to these basic guidelines – the following information should not however preclude basic common sense, which should at all times prevail and is by no means a comprehensive list of what should and should not happen on a crime scene – BUT it may go towards the preservation and collection of vital DNA evidence which may ultimately be used to convict a suspected criminal.


What Is A Crime Scene?

It is important to know and understand what is regarded as a crime scene and what can be done by the victim of crime to ensure that possible traces of evidence are secured for collection by the crime scene investigator, otherwise known as an Investigating Officer (or “I.O.” )

A Crime scene is defined as the area where a crime was committed. It is also the area where physical evidence will indicate the presence of the parties involved. The latter is based on the Locard principle which advocates that “Every contact leaves a trace” – i.e. where the perpetrator(s) of a crime comes into contact with the scene, so he will both bring something into the scene and leave with something from the scene.

Physical evidence for example, blood, semen and/or hair can easily be transferred between the victim and suspect and/or to the environment. This contact with the victim and suspect with the crime scene will leave physical evidence showing his / her presence at the crime.

Depending on the crime there may be two crime scenes, namely the body of the victim and the crime scene area where the crime occurred.


Evidence on your person:

Safeguard your body against contamination and loss of possible evidence by following the following guidelines:

  • Do not bath
  • Do not change clothing
  • Do not eat or drink (in the case of rape)
  • Do not brush your teeth or comb your hair (in the case of rape)
  • Do not urinate, and if necessary, urinate inside a closed container (in the case of rape)

Evidence on the Crime Scene Environment:

Safeguard the crime scene environment, as far as possible by avoiding contact with the scene by yourself and all other parties.

Inform the Investigating Officer of what happened. Try to remember where the attacker came in contact with the scene, for example where he walked and touched – if there was a “high contact” area, point this out to the Investigating Officer who will be able to uplift evidence such as epithelial cells, with a Dacron Swab for DNA analysis.

Did the attacker smoke, drink or eat before, during or after the attack? Where is the cigarette butt now? Did he use any eating utensil i.e. glass, spoon, fork or has he left any half eaten food at the crime scene? Did the attacker ejaculate on any surface on the crime scene? Did the attacker wipe himself? Where is the bath towel or toilet paper? This information is invaluable in assisting the crime scene investigator with the identification documentation, collection and preservation of physical evidence with real evidential value.

All the information you have supplied to the Investigating Officer must be thoroughly documented in the form of a sworn statement to be used as part of the evidence in the prosecution of the case. Any Physical evidence collected by the Investigating Officer will help prove your account of the events during the attack and link the suspect to the crime or crime scene.

An example of Effective Crime Scene Management

Each crime scene differs from the next and each must be approached and dealt with on its own merits. It can never be prescribed to the First Member or the Investigator, by means of rules and regulations, exactly how to proceed in each case. The eventual success depends entirely on his/her personal initiative, will to work and attitude towards his/her task. If the prescribed procedures are followed the solving of a case can possibly be facilitated thereby.

Never lose sight of the fact that circumstances often differ from scene to scene. The methods used by criminals change and develop with time and therefore the First Member or Investigator on the crime scene must always be prepared to learn, to replace old methods by new ones, and to devise and apply new methods.

Always remember to approach the scene rationally and calmly. Cases are solved because criminals make mistakes due to being over–hasty. Do not make the same mistakes.

Beware of becoming too self-assured. Nobody can always work alone. The First Member and Investigator on the crime scene must seek advice from others and make use of investigative aids where necessary.

The importance of the correct action at a crime scene cannot be over-emphasized. The action taken at the scene of crime by the First Member and Investigating Officer must always be correct, judicious and scientific.

Remember the following golden rules:

1. Never rely on your memory: Make notes of everything you observe in your pocketbook and / or Crime Scene Log sheets.

2. Know your definitions and elements of crimes.

3. Complaints must be given immediate attention. There is no excuse which can justify the disregarding of this rule.

4. A scene of crime must be visited, secured, protected and processed as soon as possible.

5. The relevant crime scene jackets must be worn at the crime scene.

6. The press should be courteously requested to remain outside the outer cordon of the crime scene. Refer all media enquiries to the Media Liaison Officer.

7. Never hesitate to summon help and utlize experts where it is necessary.