The Fresno Fire Department is investigating a series of arsons, three that were set within hours of each other.
The most recent fire was Wednesday morning on E. McKenzie.
Firefighters aren't sure yet if it's arson but they're not ruling out the possibility.
CBS47's Tony Botti was given exclusive access as arson investigators worked to try and solve some of the cases.
Investigators expect to have what would be consider "accidental fires" but when several arson cases stack up, that makes it more difficult as they try and piece the puzzles together.
CBS47 was given exclusive access Wednesday to shadow Christine Wilson, and investigator with the Fresno Fire Department, who is on the clock 48 hours straight. "I take everything into account from the observations of the fire crew, the observations of witnesses and then again what I see here inside the structure," said Wilson.
Many questions run through her mind as she tries to figure out what sparked a blaze, like the one at the home on McKenzie Avenue in Southeast Fresno. "I look at the burn patterns on the sofa, I look at the burn patterns on the wall..." said Wilson.
With no clear cause, evidence is packaged up and sent to the Department of Justice. They can help determine if this was a case of arson.
Koby Johns with the Fresno Fire Department said, "It's very serious if someone is going to intentionally burn their place. Whether it's insurance fraud, revenge or covering up some other crime... there's very serious consequences."
If a suspect is identified. the information is given to investigator, Lee Wilding, who is known as the "40-hour guy," because he spends four 10-hour days primarily focusing on illegal fires. "I'll make like a grocery list, a to-do-list of things I want. I need to interview this witness, I need to get these cell phone records, I need to do a search warrant at the residence," said Wilding.
Once he feels the case is strong enough for prosecution, they make an arrest, and hopefully, the team sends a dangerous person to prison. "It's really tough to prosecute an arson case, so when we successfully go through the system, then it's very rewarding," said Wilding.
Last year the City of Fresno investigated 410 fires. 171 were found to be intentional and resulted in 32 arrests. The loss from all of those arsons was estimated at $1.2 million.