The teams are each composed of veteran special agents who have post blast and fire origin-and-cause expertise ; forensic chemists ; explosives enforcement officers ; fire protection engineers ; accelerant detection canines ; explosives detection canines ; intelligence support , computer forensic support and forensic audit support . � � The teams work alongside state and local officers in reconstructing the scene , identifying the seat of the blast or origin of the fire , conducting interviews , and sifting through debris to obtain evidence related to the bombing / arson .