A serial arsonist in Minnesota was sentenced to only 90 days in a county workhouse for his fifth arson conviction because a county attorney didn't know his criminal history, according to KMSP-TV.

Alan Enger, 55, has been convicted of arson five times, is suspected in at least 73 other fires, and has admitted to setting "hundreds" of fires over the years. But, because the record prosecutors refer to uses only the last 15 years for sentencing determinations, Enger got off easy with a plea deal.

"You know, quite honestly I didn't know Mr. Enger's prolific arson history going into this," assistant county attorney Scott Haldeman told the judge. "I didn't realize he had all the previous arsons. I think 120 days is too low. I would never have offered that in the first place had I known that."

Enger was released after 78 days due to good behavior.

Enger was first convicted of arson when he was 16 for burning down a neighbor's garage. He has also been convicted in 1985, 2000, 2005, and now 2019.

According to KMSP, residents lived in fear of his arson habit. He was sentenced to 10 years by then-county attorney and current presidential candidate Amy Klobuchar in 2005 for setting fire to a duplex. He was charged as a "career offender."

That "career offender" charge could've been used in this most recent case, had attorneys been paying attention.

Enger's M.O. is simple — he gets drunk and sets fires.

"Having a little fire, drinking a beer, good time to do this now," Enger said. "Took a burning log out of a fire pit and threw through it in the truck. Next thing I know, I'm in jail."

His late mother previously referred to Enger as a "good guy" but a "total f*** up" who can't control his drinking. His brother, when informed of the light sentence, was appalled.

"Ain't it their job to look up what people's history is. F**k. He should've gotten 20 years. Don't put that on TV," Floyd Enger said.

Alan Enger indicated to KMSP that he may be done setting fires, but his lack of remorse makes arson investigator Sean McKenna skeptical.

"I don't think you can ever rehabilitate him, fire setters, sex offenders, child molesters, you don't rehabilitate them," McKenna said.