http://www.kdbc.com/Global/story.asp?S=10828753&nav=menu608_2_
I am not so sure about the summer thing... yet...
I'm not sure either.
"Robert lives with his father in New Plymouth, but was visiting his mother and her family Friday, police said."
http://www.idahostatesman.com/eyepiece/story/847786.html?commentSort=TimeStampDescending&pageNum=1
He was visiting on Friday. But we don't know if he had just gotten there that day, or if he had been there for a while.
But on another yet somewhat related note, I also remember police trying to put together a timeline of Robert's activities on Friday. So...they must have reason to believe that he was alive up to Friday.