The contents of the note were not released.
Court records show a man who killed his ex-wife and two young sons before fatally shooting himself in Minneapolis on Sunday left a suicide note at the scene.
The Star Tribune reports a search warrant unsealed Tuesday does not reveal the contents of the note.
A medical examiner identified the victims as 39-year-old Kjersten Schladetzky, and her sons, 8-year-old Nelson and 11-year-old William. The boys' father was 53-year-old David Schladetzky.
Authorities say the children were shot outside the home where they lived with their mother, who was shot and stabbed inside the house. Court records show David Schladetzky had never been the subject of a protective order or faced charges beyond minor traffic infractions.
Court records show the couple agreed to joint custody of the children when they divorced in June.