PHOTO GALLERY: A look at how fire investigators asses fire scenes

Lt. Shawn McCollom, a fire investigator for the Columbia Fire Department looks through the photos he took from the scene of a fire at his office at the Columbia Fire Department on Wednesday. As a fire investigator, McCollom goes to fire scenes where he takes pictures and notes to make an analysis of the cause and damage.   |  Yi Gan

A floor plan drawn by Lt. Shawn McCollom during an investigation sits on his desk Wednesday. He often draws a floor plan at a fire to help him write the analysis after he comes back to his office.   |  Yi Gan

A light bulb that pointed to the direction of a fire is displayed in Lt. Shawn McCollom’s office on Wednesday. According to McCollom, an incandescent light bulb may appear as “pulled” in a fire because the gas inside the bulb expands and pushes out the softened glass on the side closest to the heat source.   |  Yi Gan

This photograph shows the scene of a fire at 5107 Hatteras Drive on Feb. 16. The fire originated beneath where the floor is caving in at the home in Columbia. The area of most intense damage was directly above where the fire originated in the basement.   |  Photo Courtesy of Lt. Shawn McCollom

Often a V-pattern helps fire investigators find the point of origin for a fire. The cause of this fire was a shop light on a shelf. The V-pattern can be seen in how the timbers are untouched near the floor and the burn pattern is up and out from the shelf.   |  Photo Courtesy of Lt. Shawn McCollom

As a fire investigator, Lt. Shawn McCollom looks through a scene he pays attention to whether a door has smoke on both sides. One side of the door in this Columbia home is clean, showing that the door was closed at the time of fire.   |  Photo Courtesy of Lt. Shawn McCollom