Kris-Deann Sharpley and her Monday son were found dead on seven year old . Her father Derek was also found at the Biddeston house , near Brisbane . Detective Inspector David Isherwood said the grandfather had a history of criminal behaviour and mental health issues . The child 's cause of death remains unknown as initial pathology results were unclear , but suffocation and strangulation are still being investigated . The owner of the gun used in the homicide also remains unknown . Police say the deaths of the boy and mother are suspicious but the death of the man is not suspicious .
Kris-Deann Sharpley and her seven year old son were found dead on Monday . Her father Derek was also found at the Biddeston house , near Brisbane . Detective Inspector David Isherwood said the grandfather had a history of criminal behaviour and mental health issues . The child 's cause of death remains unknown as initial pathology results were unclear , but suffocation and strangulation are still being investigated . The owner of the gun used in the homicide also remains unknown . Police say the deaths of the boy and mother are suspicious but the death of the man is not suspicious .