MINNEAPOLIS (WCCO) – A man convicted of using a shotgun to murder his mother in 1995 has pleaded guilty to illegal possession of firearms.

Christian Oberender, now, 34, was sentenced to 40 months behind bars and 20 months on supervised release.

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Oberender was found with assault rifles he acquired by lying on various background checks.

He was barred from owning firearms, but the Bureau of Criminal Apprehension did not have accurate records of the 1995 murder.

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He was able to get a gun permit in summer 2012.

Carver County Sheriff Jim Olson led the investigation into Oberender’s arrest based on a citizen’s tip.

“Never, and I mean never, should a person who has been deemed mentally ill and dangerous be allowed to purchase a handgun,” Olson told the AP.

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Authorities seized all 13 of Oberender’s guns. He will be fined $2,000 “plus applicable surcharges.”