Arson Ivestigation

Let’s begin with the crime of Arson as defined in the Victorian Crimes Act 1958 under section 197 (1)

Destroying or Damaging property

A person who intentionally and without lawful excuse destroys or damages any property belonging to another or to himself and another shall be guilty of an indictable offence and liable to level 5 imprisonment (10 years maximum).

An offence against this section committed by destroying or damaging property by fire shall be charged as ARSON.

There are many persons involved in a successful fire investigation including the Forensic Fire Scene Examiner, the Fire Investigator, forensic accountants and forensic locksmiths to name but a few.

The Forensic Fire Scene Examiner, first and foremost, needs to establish there is a deliberate fire or arson. The scene needs to be forensically examined.

We need to establish the area of origin of the fire, the point of origin of the fire, then the cause of the fire.

Area of Origin

In the instance of a building structure fire, where did the fire start in the building?

We can’t begin to establish the cause until we know where the fire started.

Fire creates evidence as it burns, the trick is reading the available evidence left after extinguishment.

It requires a methodical approach.

We begin by observing the area of most damage to the area of least damage.

Then we look for burn patterns evident in the area of most damage.

What are burn patterns?

There are many different burn patterns within a fire scene which help the forensic fire scene examiner determine the origin and cause of a fire. Among them are splash patterns where accelerants are used and inverted V patterns.

Fire burns upwards and outwards.

When a fire burns against a combustible wall, it creates an inverted "V" pattern.

The base of the V can help us determined the point of origin.

(note: There can often be more than one point of origin).

V patterns vary dependent on the fuel load present.

An available materials fire, paper for instance, creates a wide inverted V pattern.

An accelerated fire, petrol for instance, creates a narrow inverted V pattern.

Sources of ignition

Once we establish a point of origin, we look to determine a cause of the fire within the point of origin.

What ignition sources are present to start a fire in that area?

To prove arson, we must also eliminate all accidental sources of ignition, such as electrical.

Samples may be taken from the point of origin and forensically examined.

If the examination reveals the possible presence of an accelerant, the use of gas chromatography is used to examine samples for the presence of hydrocarbons such as, but not limited to, petrol.

Canine detectors

In the USA, Canada and the UK canines trained to identify accelerants are sometimes used. We tend not to use them in Australia.

Motives for Arson

Let’s consider the motives for Arson; the reasons people commit Arson.

If confronted by an arson fire, we need to establish a probable motive. Whilst it is not required for a successful prosecution, it is a helpful start to an investigation.

Intimidation

• When an individual uses fire or the threat of fire to intimidate another person or persons to gain some sought of perceived advantage.

Concealment of crime

• When an individual uses fire to conceal their involvement in another crime. Example, you often see vehicles set on fire by persons involved in a serious crime to remove any trace of DNA or fingerprints

Revenge

• When an individual seeks retribution against another, to square the slate.

Economic Gain

• Used by individuals in a failing business, in an attempt to secure a favourable insurance claim. We consider the financial viability of the business, forensically examine financial records, any recent attempts to offload the business, the security of the premises, who had keys, who was the last to leave.

Pyromania

• These individuals get pleasure from setting fires.

Thrill Seeker

• These individuals celebrate the chaos created by setting fires.

Factual Investigation

Once motive is established, the direction an investigation takes is often clearer.

The arson investigator seeks:

• The assistance of eyewitness accounts and observations of those at the scene at the time of the fire;

• Evidence of suspicious or unusual behaviour by individuals at the scene before or after the fire;

• Observations of fire behaviour prior to the arrival of fire fighters;

• Observations of the fire fighters first on the scene;

• In particular, points of entry to the building, was the premises securely locked or was there evidence of forced entry; and

• Evidence provided by the forensic fire scene examiner examination of the scene.

Once the motive is established, the investigation will identify witnesses and potential suspects to be interviewed. The perpetrator will then be interviewed, a brief of evidence prepared then presented to a court of competent jurisdiction, (Magistrates Court, County Court or Supreme Court).

Written by Terry McCabe (former arson investigator)