Now, to the man bites dog story. The Minnesota fire chief who admitted to setting fires in his community. "20/20" anchor Elizabeth vargas has been working on this story. And the chief's explanation as... See More
Now, to the man bites dog story. The Minnesota fire chief who admitted to setting fires in his community. "20/20" anchor Elizabeth vargas has been working on this story. And the chief's explanation as to why is just as surprising. Definitely. There were 39 suspicious fires around the town of Bab at, Minnesota. Imagine the shock in the town when the town's new fire chief, a new father with a brand-new baby, confessed to setting those fires. And the reason? It was all about the baby. When the tiny down of Babbitt, Minnesota, had an unexplained spike of suspicious fires, investigators gravitated towards a theory. That the fire starter could be a firefighter. Believe it or not, it happens more often than you think. It's a dirty secret. If you just do an online search, you will find about 100 firefighter arrests every year in this country, for arson. A part-time firefighter has been arrested for arson. A former volunteer firefighter. Reporter: The theory that the Babbitt arsonist may be one of the firemen developed into suspicion, when the fire chief was caught one night on 79-year-old don matly's property, with a gas can that was half-full. What did you think he was doing back there with the gas can? What do you think? Reporter: Starting the fire. I never poured gas on anything. I never tried to light a match. I never physically attempted to start a fire. Reporter: But you brought the gas can there. It was in the trunk of my car at the time, from a few days earlier, I think from filling it up. Reporter: Investigators for state and local agencies believe they had found their fire starters. They confronted Scharber with that gas can. And he confessed. Including to nine fires. And more stunning than his criminal behavior, his excuse. He says it was stress, brought on by a constantly crying newborn son, Aidan. It was just when I was home. And the stress that caused me to go out and start the fires. At work, I didn't have that. Reporter: People are going to say, I don't get this. I don't get it. Millions of babies around the world have colic. Their dads don't go out and set fires. It was a legitimate way for me to get away for a couple of hours. Reporter: Why not go down to the firehouse and hang out with your fellow firefighters? How was it that you thought, I know, I'll go set a fire? People are coming to me for help. I was solving people's problems. I realized I needed a little he help myself. Ryan was sent to five years in prison for the stress of his newborn son. You and I had a colicy baby. It is stressful. We were discussing it earlier. Neither one of us thought -- No. I was a little cranky the next day. And his story was inconsistent throughout all of this. He didn't exactly say the same story each time he was questioned. Absolutely. For 2 1/2 hours under questioning, he tried to implicate other Babbitt firefighters. He was trying to implicate others, until finally confronted with the gas can. But he continues to minimize. They were only grass fires. But investigators and authorities say by the grace of god. We'll have a lot more on the story tonight, on "20/20."
This transcript has been automatically generated and may not be 100% accurate.