Not exactly. Remember that Laci's body was never fully recovered and the time and cause of death were never determined. If the murderer buried the body in his back yard then learned of the search, removing it to the bay would tend to frame Scott.
Now look at it another way...So you're saying that Scott killed Laci then dumped her in the bay 90 miles away then came home and told everyone that he had gone fishing in the bay 90 miles away?
I don't know how smart Scott is, but he is a college grad, and it would not take a lot of smarts to say that he had gone fishing somewhere else...like in the opposite direction from where the bodies were found.
Scott doesn't impress me as smart. I just has gotten away with everything in life and probably believed it was the natural state of affairs.
And the 3 people that saw him at THAT marina? How would you have explained that?
Ah hah....you missed the point...Some working dudes at the Marina saw him. He couldn't say something else at this point.