Background: News footage of the home in Holmesville Township, Minn., where Gene Bartnes and his son Koltyn were found dead on March 30 (KVLY). Inset: Gene Bartnes holding his son Koltyn (Facebook).

Police in Minnesota confirmed that a father and son found fatally shot were victims of a murder-suicide.

Gene Bartnes, 45, and his 3-year-old son Koltyn were found dead of gunshot wounds on Monday afternoon after Bartnes' brother went to the home to check on them. According to the Becker County Sheriff's Office, Bartnes' brother became concerned when the father did not show up for work that morning. When the brother entered the home, he found Bartnes dead. Deputies later found Koltyn's body.

On Tuesday, police confirmed that Bartnes killed his son before turning the gun on himself. Koltyn's mother and surviving siblings revealed more details about the killing, including the three suicide notes Bartnes left behind.

In an interview with local NBC affiliate KVLY, Kristi Frazier, Koltyn's mother, said that police told her about how her former partner and toddler son died. Frazier told KVLY that Koltyn was shot in the back while he was asleep, "then his dad crawled into bed next to him and shot himself in the chest."

Frazier said Bartnes had possibly suffered from mental health issues. Her landlord told her that when he saw Bartnes prior to his death, he "seemed off."

The mother told KVLY that Bartnes reportedly left three suicide notes — one for her, one for law enforcement, and one offering an apology for his actions. Frazier said she had not been able to read any of the notes after police confiscated them as part of their investigation into the deaths.

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On a GoFundMe page started to support Frazier, a friend noted that Frazier was a day care provider for her community. The family told KVLY that the funeral was currently on hold.