I would encourage anyone not familiar with Joseph Duncan to read this short synopsis of the case :
It is so easy to look at the family.
That is what I did in this case. I was absolutely convinced it was the father or one of his friends, because of his background.
No one ever could have dreamed this monster exisisted!
When you read how this man operates you will see how hard a job LE has.
God forbid it's another Duncan.
On May 16, 2005, Kootenai County, Idaho authorities discovered the bodies of Brenda Groene, 40; her boyfriend, Mark McKenzie, 37; and her son, Slade Groene, 13, in their home along Lake Coeur d'Alene, outside the city of Coeur d'Alene. Two of Brenda Groene's other children, Dylan, 9, and Shasta, 8, were missing. An AMBER Alert was issued and searchers combed the area for the missing children while authorities investigated the deaths at the home as homicides. Autopsies determined the cause of death to be "blunt trauma to the head"; authorities also noted that the victims had been bound.
http://murderpedia.org/male.D/d/duncan-joseph-edward.htm