Autopsy reports show that the New Town woman and three of her grandchildren found slain in their home earlier this month were gunned down with a hunting rifle.
The state medical examiner concluded that 64-year-old Martha Johnson and 13-year-old Benjamin Schuster were shot in the head, 10-year-old Julie Schuster was shot in the chest and 6-year-old Luke Schuster was shot in the neck.
Dr. William Massello estimated they died within six minutes of one another on Nov. 18.
A man who killed himself later that day in nearby Parshall is considered a person of interest in the case.
The autopsy report says 21-year-old Kalcie Eagle of New Town died after cutting his own neck.