I'm sure del rio and the other person who drove by as the LE found the body can confirm that it really does NOT appear that they wanted her body found. You have to go to this property before you can make a statement like this because it is like a jungle there. I will link these pictures again: http://www.kirotv.com/slideshow/news/22603743/detail.html
Pictures 2 and 3 are misleading because the body was found about 500 feet from here. Look at picture 5, behind the police in the thick brush is where her body was discovered. This beach is NOT an area frequented by people and I highly suspect the killer was very shocked her body was discovered so quickly.
Correct me if I'm wrong, but isn't the water pretty low this time of year at the river. I've seen the Columbia get pretty high and fast during the spring. If they put the body in the brush next to the water and waited for spring runoff, the body could have washed away on it's own at a later date and no one would have been the wiser to where it had been. It would then have possibly been found much further downriver. If the water didn't rise, then what are the odds that someone would find the body before the house was bought and someone tried to landscape or do something with that area, if ever. By the time that happened there would be nothing but bones that might never have been found either. I agree that the killer didn't think anyone would be walking along that beach especially with the house being vacant.