BOISE - As fire investigators prepare for fire season, Thursday agencies from across Idaho gathered in the Boise desert for a tune-up exercise to get ready for the upcoming season.

When fire investigators get out to burned scenes, they have a very complicated puzzle to solve.

After hundreds and hundreds of hours of training though, Idaho fire investigators are able to determine the cause of a fire and why it spread the way it did.

Idaho Department of Lands Fire Investigation Manager Bob Helmer says every fire is a challenge.

"It's very difficult, I mean, you are putting together a jigsaw puzzle," said Helmer.

MORE: Local fire crews take to the sky to survey Boise Front

During Thursday’s training, fire investigators from across the state worked to solve simulated fires.

"Each of the plots will have a different theme to them some will be shooting, some will be fireworks, some will be campfire, they could be cigarette butts. Each one is going to have a different start and maybe more than one start," said Helmer

There are fires that are caused naturally, but the IDL says a large number of fires are human-caused. Take 2017 for example, out of the 213 total fires on IDL land, 147 of them were human-caused.

Helmer says solving all those fires is difficult work that takes a lot of training and close attention to detail.

"We will be out there on our hand and knees with a magnifying glass and magnets and stuff looking for the evidence," said Helmer.

When you look close enough though, every detail help tells the story.

"There is indicators on all the grasses, wood, trees, and structures that you can follow to see where the fire burned," said Helmer.

The canvas of the puzzle usually starts as a blackened mess, but after a close look at the clues, investigators populate the landscape with colored flags that all lead to an answer.

"The red is for advancing fire, the yellow is for a lateral fire and the blue is for a backing fire. The green ones out there are for things of interest, evidence, footprints, charred material that they would want to look at further, and the white one they use as their origin," said Helmer.

Fire investigators say getting some practice in before the busy season really helps keep them fresh.

"This is extremely valuable. You really need to do something like this every year before fire season to get tuned up and ready to look at the indicators, and thinking about what to do, and to talk with the other agencies to see what they are doing," said Helmer

The real takeaway that fire investigators want you to take home this summer is that if they do find out that you set a fire negligently - they will bill you.

The IDL says they are in the process of billing over $3 million to people who started negligent fires last year.

All money collected by the IDL for fire bills goes into the fire preparedness fund. That fund helps the IDL hire more firefighters and put more equipment in place prior to fire season.

Fire investigators really want people to keep that in mind that when you are out in dry areas, play it smart and come prepared.

Something to also keep in mind if you are going to be out on protected land this summer, "closed fire season" runs from May 10 through October 20.

During that time, it is required to get a fire safety burn permit from the IDL before starting certain controlled-burn activities.