| After a fire is put out and CSI technicians or fire | | | | well. Furthermore, an arsonist may have set various |
| investigators arrive to look over an arson crime | | | | fires within a building or spilled a path of charcoal fluid |
| scene, the first thing they want to know is where | | | | or other accelerant throughout or around the |
| the fire started. They will look for clues to determine | | | | structure, thus setting a fire with more than one |
| its origin. | | | | point of origin. |
| Finding a fire's point of origin requires knowledge of | | | | By assessing the fire's effect on structural materials, |
| how a fire moves through a structure. In general, | | | | CSI's can estimate the intensity of the fire at any |
| fires spread sideways and up from the point of | | | | particular place. Under extremely intense heat, steel |
| origin, but that pattern can change due to structural | | | | beams buckle, and glass melts at around 1,500 |
| and decorative elements of the building. For example, | | | | degrees Fahrenheit. Crackling and flaking on floors and |
| stairwells may force a fire in one direction, and the | | | | walls are indicative of places of high heat. Likewise, |
| chemicals in man-made carpet may cause abnormal | | | | wooden beams, walls, and floors may scorch leaving |
| burn patterns. Usually, the biggest amount of damage | | | | an alligator skin-like pattern in the wake. Whenever |
| happens near the point of origin. CSI's look for | | | | this occurs, smaller scales tend to be closest to the |
| evidence of igniters or accelerants as possible clues | | | | hottest point of the fire. |
| that suggest a point of origin. | | | | If smoke detectors are present throughout a |
| Other factors than can influence or hinder CSI's' | | | | structure, the time at which each alarm was set off |
| efforts in determining a point of origin are open | | | | can help CSI's ascertain the path that the fire |
| windows, stairwells, or materials used to build or | | | | traversed throughout the building and locate the point |
| decorate the building. | | | | of origin. |
| After determining the point of origin, a CSI | | | | Liquid and volatile fuels pose special problems for |
| sometimes can retrace the fire's trajectory even | | | | arson investigators because they spread more quickly |
| when the building has undergone heavy structural | | | | and take the shape of their containers. If the |
| damage. On the other hand, backtracking along the | | | | perpetrator of an arson sloshes paint thinner on a |
| fire's path may yield the point of origin. | | | | floor, the paint thinner spreads across the room, runs |
| Searching for a V pattern in burned material is | | | | down the stairs, and oozes into the baseboards. |
| another way of finding the point of origin. It is the | | | | Upon igniting the paint thinner, the fire follows the |
| tendency of fire to rise and spread so that it burns a | | | | liquid and spreads right away, making the point of |
| wall or other vertical surface in a V pattern, with the | | | | origin widely spread out. |
| point of the V located at the origin of the fire. | | | | Volatile fuels like methane gas diffuse in all directions |
| Fuel containers and other flammable liquids also can | | | | until they fill their containers. Upon lighting up this fuel |
| not only hinder the search for the true point of origin | | | | source, these containers can explode. Finding an |
| but also with the locating of arson-related | | | | exact point of origin in this scenario is impossible. |
| accelerants, simply because they are accelerants as | | | | |