APPLICATION OF THE SCIENTIFIC METHOD IN THE DETERMINATION OF ORIGIN AND THE CAUSE OF A FIRE

We want to deliver a clear and simple application tool to our colleagues who carry out investigative work in the region, this document seeks to complement when defending our report at the judicial level, and serve to order the work done in reference to the application of the scientific method to our research. References to NFPA 921-2017 and general recommendations are also included at this point.

4.2. Systematic approach. The recommended systematic approach is based on the scientific method, which is used in the physical sciences. This method provides the organization and analytical processes that are desirable and necessary to successfully conduct a fire investigation.

4. 3. 6. 1. * Any hypothesis that cannot be tested physically or analytically is an incorrect hypothesis. A hypothesis whose development is based on the absence of data is an example of a hypothesis that cannot be tested. The inability to refute a hypothesis does not mean that the hypothesis is true.

4. 3. 7. Avoid Presumptions. Until the data has been collected, a hypothesis cannot reasonably be formulated or contrasted. All investigation of a fire or explosion incident should be focused without a presumption as to its origin, ignition sequence, causes, spread or liability, until the use of a scientific method leads to probable hypotheses

4. 3. 9. * Confirmation bias. Different hypotheses may be compatible with the same data series. When using the scientific method, hypothesis testing must be designed to refute specific hypotheses (hypothesis falsification). Confirmation biases occur when an investigator tries to test a hypothesis. This may result in a failure that leads either to consider new hypotheses, or to prematurely discard apparently conflicting data without proper evaluation. A hypothesis can be said to be valid only when the most rigorous tests have failed to refute it.

4. 5. Level of Certainty. The level of certainty is a measure of the Strength with which someone maintains an opinion (conclusion). People can hold an opinion with a high or low level of certainty. This level is determined by evaluating the researcher's confidence in the data, data analysis, and testing of the hypotheses presented. The level of certainty can determine the practical application of the opinion, especially in legal proceedings.

4. 5. 1. The researcher should know the level of certainty required to be able to express expert opinions. The two commonly accepted levels are probable and possible:

• Probable. This level of certainty corresponds to a greater probability that it is true than not. At this level, the probability that the hypothesis is true is greater than 50%.
• Possible. At this level, it can be shown that the hypothesis is possible but it cannot be considered probable. If there are two or more hypotheses with the same level of probability, the level of certainty will be considered “possible”.

4. 5. 2. If the level of certainty of an opinion is barely “suspected”, the opinion cannot be qualified as the opinion of an expert. If the level is only “possible”, it should be stated expressly that the opinion is “possible”. An opinion should only be stated as reasonably true when the level of certainty is “probable”.

Remember to take special care during the excavation and reconstruction of the fire site as physical evidence of vital importance to the investigation may be affected. Spoliation, or evidence damage, must be avoided at all costs; The contamination of the signs must also be avoided, extreme care must be taken in the use and lifting of combustible or other liquids during removal. Avoid Negative Corpus, or issue criteria without scientific basis.

Application of the Scientific Method Determination of Origin

1.- Recognize the Need: A fire has occurred and the origin is unknown.

2.- Definition of the Problem: The Origin of the Fire must be determined.

3.- Data Collection: In general, the data related to the establishment of the origin are: the basic data of the site, determine the pre-fire conditions, document the post-fire conditions, debris removal, exploration and reconstruction of the scene . The statements of witnesses, first responders and observers, alarms, detectors and data security.

4.- Data Analysis: The analysis of the data collected together to determine: pattern of analysis, heat and vector analysis of the flame, depth of charring, arc mapping (if applicable), sequence sequencing, considerations general of fire dynamics and finally the own considerations of the building and its occupation.

5.- Development of the Hypothesis: I must clearly establish which is my “Hypothesis of the Origin of Fire”, hypotheses of the initial origin, hypotheses of the origin work and alternative hypotheses.

6.- Hypothesis Testing: This is where we separate inductive reasoning from deductive reasoning; testing our hypothesis, contrasting it with mathematics and laboratories (if necessary).

7.- Selection of Final Hypothesis: Here the researcher must be very conscious and critical of his own work, the final hypothesis must consider a "Place of Origin" and a "Point of Origin" and / or establish an Insufficient Origin to determine the cause.

Application of the Scientific Method Determination of the Cause

1.- Recognize the Need: A fire has occurred and its cause is unknown.

2.- Definition of the Problem: The Point of Origin has been determined, now the cause of the fire must be determined.

3.- Data Collection: The data related to the cause of the fire are very different from the data of the origin, the data of the cause of a fire has to do directly with: Identification of the fuels present in the area of origin, identification of possible sources of ignition, identification of oxidizing agents, identification of the circumstances that make possible the interaction of the source with the point of origin.

4.- Data Analysis: The analysis of the initial fuel data (ignition temperature, quantity, density, geometric arrangement, etc.), analysis of the ignition source (temperature, energy and time), analysis of the oxidizing agent ( An extended explanation should be made when the oxidizing agent is different from O2), analysis and description of the possible identified ignition sequences.

5.- Development of the Hypothesis: Consider that I must establish different hypotheses for each possible source of ignition, you must consider the possible lack of sources of ignition, you must propose the initial fuel for each source. Always consider alternative hypotheses.

6.- Test of the Hypothesis: To verify the cause hypothesis, it must be clearly established if the ignition source was located at the origin, I must establish that the proposed source is capable of burning the initial fuel and if it had enough time For this end. The proposed cause must be consistent with all known facts, all contradictions must be resolved and other hypotheses that can explain the data must be sought.

7.- Selection of Final Hypothesis: Here again the researcher must be very aware and critical of his own work, the final hypothesis of the cause must clearly establish: cause of the fire, list of possible causes or, failing that, indicate the lack of information to determine the cause.

In my work as an international instructor and accredited expert in Chile and Ecuador, I have realized that the predominant factor, when successfully facing a trial process, is the practical application and above all reasonable doubt of the scientific method, this It is the work that we have assumed as a training challenge for the agencies with which we work (Mexico, Chile, Ecuador, Peru and Argentina, directly and indirectly the rest of Latin America, plus Spain, Portugal and France.

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