In arson cases, eyewitnesses are rare. Fingerprints are covered in ash and soot if not destroyed. When firefighters put out fires, they unknowingly destroy evidence.

These and other factors make arson cases uniquely challenging for investigators and prosecutors.

Since 2000, the District Attorney’s Office has assigned prosecutors to specifically address arson cases. Now known as the Arson and Explosives Section, it is comprised of three experienced prosecutors who are based in downtown Los Angeles but handle cases throughout the county.

The section prosecutes cases that result in death or serious injury to innocent victims and firefighters and cause millions of dollars in damage. Recent cases include the massive Da Vinci apartment complex fire in downtown Los Angeles in 2014 and a Pasadena house fire that killed two men in 2012. Prosecutors also assist other units in the office and outside agencies with their cases.

Arson and Explosives Section prosecutors work closely with local, state and federal arson and explosives investigators.

"Prosecutors are involved in arson investigations at the start," said Deputy District Attorney Joy Roberts, who has been with the section for two years. Roberts and her colleagues Rachel Bowers and Holly Harpham accompany investigators at crime scenes. Working closely with investigators is a significant plus, Roberts said.

“When you’re able to be right there, you can see what they see. You don’t have to think about it in the abstract by reading it in a report,” she said. “You can also help advise them about what makes a successful prosecution, such as things to photograph that a jury would appreciate.”

The prosecutors must understand the science of fire and explosives investigations to analyze law enforcement reports and evidence. They take part in trainings given by a host of agencies.

One training involves processing of crime scenes with human cadavers. Other trainings cover fire dynamics, the science of determining a fire’s cause and origin and fire effects on the human body.

Courses on explosive devices have covered homemade explosives and booby-traps used to thwart law enforcement. In one class, students watch live pyrotechnic and explosives detonations on the demolition range, then work to reconstruct what occurred.

“The training is fascinating and far from typical,” Roberts said. “But it is absolutely necessary to understand the complexity of the cases we prosecute.”