Not only that, but a true sociopath can often ace a polygraph, while someone who's not guilty, just nervous and scared, can fail them. I think he had good advice, probably from his father, an ex-judge. After Scott Peterson and Mark Hacking, I don't blame anyone for suspecting him--and I don't blame him for protecting himself. That ditzy would-be bride of his might have just left him to twist in the wind.
If she had holed up somewhere and stayed missing, I think more and more people would have been pointing at him. The Laci Peterson case was in my mind, too. I'm elated that she wasn't murdered, but I think that letting her loved ones think she had been abducted was inexcusable.