Man receives 51-year sentence for Otter Tail County murders A judge earlier rejected William Hillman’s mental illness defense and found him guilty of fatally beating 42-year-old Denise McFadzen and her son. Credit: Otter Tail County Sheriff William Hillman mug shot Published: 9:18 AM CST January 28, 2021 Updated: 9:39 AM CST January 28, 2021 FERGUS FALLS, Minn. — A 24-year-old man with a history of mental illness has been sentenced to serve more than three decades in prison for killing a woman and her adult son in Otter Tail County. A judge earlier rejected William Hillman’s mental illness defense and found him guilty of fatally beating 42-year-old Denise McFadzen and 21-year-old Dalton McFadzen at their home north of Perham in April 2018. The McFadzens had allowed Hillman to live in their home in Gorman Township.