A "sick-minded" dad stabbed his entire family to death before turning the knife on himself just days after he had been released from a mental health facility. Jeremy Koch, 42, killed his wife, Bailey, 41, and son, Hudson, 18, and Asher, 16, before using the blade on himself on Saturday, May 10.

Police with the Dawson County Sheriff's Office, in Nebraska, were dispatched to the home in rural Johnson Lake, about 172 miles west of the city of Lincoln, and found four bodies inside the property. All members of the family were found with stab wounds, according to police.

The Nebraska State Patrol (NSP) said in a statement that it is believed Koch "killed each of his sons...and his wife...before taking his own life." A knife was found at the scene.

Teenager Hudson had been due to graduate from Cozad High School just hours after the killing

The Mirror reports Koch is understood to have fatally stabbed members of his family and turned the knife on himself just three days after he was released from a mental health hospital. The NSP said a homicide investigation is being carried out to learn the circumstances of the events leading up to the killing.

Lane and Peggy Kugler, the dad and mother of Bailey and the grandparents of the two children, shared a heartfelt Facebook tribute, which can be viewed in full here, to her daughter and about Koch's history with mental illness. They added: "Jeremy had been fighting mental illness for many, many years. His depression had turned into psychosis. It was not Jeremy who committed this horrific act. It was a sick mind.

"Bailey, Jeremy and the boy’s faith was very strong. It really helped them through the worst of times. We find strength in our belief that heaven now has four new angels sitting at the right hand of God. They are together and Jeremy’s sickness is gone.

"Bailey fought so hard to help him and she and her sons lived in fear of the possibility of losing her husband and their father to mental illness for many years. They never knew when he would be in a manic state (super high) or horribly depressed (super low), unable to function normally.

"Bailey fought so hard to bring attention to those who needed help. She was a huge advocate for mental health. She spent countless hours on their Facebook page, Anchoring Hope for Mental Health: Jeremy & Bailey Koch. If you go to that page, you can read about how so many people thanked her for her open and honest writing about mental health."

The NSP added: "The investigation remains ongoing. The Nebraska State Patrol, the Dawson County Sheriff’s Office, Eustis Fire & Rescue, and the Dawson County Attorney extend condolences to all, across multiple communities, who will be affected by this incident."

For emotional support you can call the Samaritans 24-hour helpline on 116 123, email jo@samaritans.org, visit a Samaritans branch in person or go to the Samaritans website.