The defendant's name was Patrick Larry Dean Morgan.  While showing off a foreign brand rifle he had stolen in a burglary,  it discharged and killed a juvenile girl while two other juveniles watched.  He was prosecuted and convicted as an adult.  I was able to get Circuit Judge Edwin E. Allen to acquit him on the UUMV charge and he also  is the Judge who upbraided Patrick's mother in open court.  That was done in a Motion to Suppress Hearing on the Manslaughter case.  I was admitted to the Oregon State Bar in 1971.  As far as the law authorizing that prosecution and conviction, do your own research.