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| Imagen tomada de Forensic Magazine |
Algunas de las consideradas "reglas de oro" en el estudio de incendios, que podían ser signos de la presencia de algún acelerante para iniciarlo o provocarlo, según los expertos no son signos inequívocos. Discover Magazine publica lo que denomina Siete mitos a cerca de los incendios:
Seven Myths About Arson
10.24.2011
Fire investigators
have long used certain rules of thumb to identify arson. Many have been proved
incorrect.
by Douglas Starr
1. Crazing of windows, in which hundreds of
cracks appear in the glass, indicates rapid heating and means an accelerant was
used to start the fire. REALITY: Crazing is caused by the rapid cooling of
window glass, as when water from a fire hose strikes a hot window.
2. Burn marks on the floor indicate that a fire
was purposely set, because heat rises and fire only burns upward. It must have
been set by pouring a liquid on the ground and lighting it. REALITY: When a
fire reaches flashover—the point at which an entire room ignites—extreme
radiant heat will produce burn marks or even burn holes in the floor.
3. Melted metals, such as doorway thresholds,
indicate that a liquid fire starter must have been used in order to reach
temperatures that exceed their melting points. REALITY: Wood fires, especially
those that reach flashover, frequently exceed the melting point of metals.
4. Burn marks under doorway thresholds or under
furniture indicate that a liquid accelerant must have been used to start the
fire, since the liquid must have been poured and then seeped. REALITY: Post-flashover
fires commonly cause burning under thresholds and furniture.
5. Spalling, or surface chipping of concrete,
indicates that a liquid accelerant must have been poured on the concrete
surface and lit. REALITY: Many factors can cause this effect, including
differential expansion between the heated surface and the interior. Accelerant
poured on the concrete actually protects it by providing a cool, evaporative
surface.
6. Alligatoring, the appearance of blisters on
the surface of burned wood, points to a fire’s origin. Small, flat blisters
result from a slow burn; large, shiny blisters indicate rapid heating and hence
the use of an accelerant. REALITY: There is no scientific evidence for any such
correlation. Both types of blisters can appear on the same burned wall.
7. Sharply angled V-pattern burn marks on a wall
denote a fast-burning fire that must have been started with a liquid
accelerant. REALITY: Patterns can result from a number of factors, including
ventilation, air currents, location of fuel, and the materials burning objects
are made of.
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| Imagen tomada del artículo original de Discover Magazine |
¿Consecuencia o coincidencia?
La Comisión de Ciencias Forenses de Texas recomendó que se revisen todos los casos de condenas relacionadas con incendios y emitió 17 recomendaciones, entre ellas que se de capacitación avanzada a los expertos y que se apeguen a estándares nacionales.
La referencia se encuentra en Huffintong Post
http://www.huffingtonpost.com/2011/10/28/rick-perry-texas-forensic-science-commission_n_1064561.html
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