A welfare check on the morning of March 5, 2023, at a home on Brunswick Road in Fish Lake Township, Minnesota, produced a triple homicide. Kirk Patrick Mattson, 47, was found inside the residence with multiple gunshot wounds; his parents, 73-year-old Darrell James Mattson and 68-year-old Denise Lillian Mattson, were also found dead from gunshot injuries. Family members had requested the check after they could not reach Kirk or his parents.

Investigators focused on a relative, 39-year-old Kenneth G. Koslowski of North Branch, who had been found dead the previous day, March 4, in a rural part of Dakota County from an apparently self-inflicted gunshot wound. The gun recovered with Koslowski was forensically linked to evidence from the Mattson home, and authorities say they suspect Koslowski killed the three family members before his own death. No motive has been released and officials have stated there is no ongoing threat to the community.

If anyone knew the Mattson family or has information about Kenneth Koslowski’s contacts or movements in late February and early March 2023, please share what you know with the Chisago County Sheriff’s Office or the Minnesota Bureau of Criminal Apprehension.