MINNEAPOLIS (WCCO) — A former Mille Lacs County Sheriff’s deputy could face up to 33 years in prison after pleading guilty to criminal sexual conduct charges involving young boys that he took on fishing trips.

According to the Minnesota Department of Public Safety, Aaron Joseph Heuer of Isle, Minn. pleaded guilty in Otter Tail County District Court to four counts of first-degree criminal sexual conduct and one count of second-degree criminal sexual conduct.

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He also agreed to plead guilty to one count of first-degree criminal sexual conduct in Mille Lacs County.

Heuer’s assault charges involve five male victims, who were 8-10 years of age at the time of the incidents. He admitted to inappropriately touching four of the boys as part of his plea deal.

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The former deputy allegedly assaulted the victims on two separate fishing trips in June 2013: one at the Lutheran Island Camp in Henning, Minn. and the other in Aitkin County.

According to a criminal complaint, the victims said the assaults happened on boats, and Heuer would threaten to toss them into the water if they did not submit to his sexual demands.

Authorities believe Heuer knew the victims before the incidents.

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Heuer’s sentencing is scheduled for May 8.