Obviously someone removed her without leaving evidence, so why not him? No, the perp left prints on both "alarm-light" doors, the bannister, Danielle's door-frame and her dresser. He/she also left DNA all over her bed.
It's just that the evidence doesn't match DW, so we don't look at it.
So we know that the "evidence" found in Danielle's bedroom and elsewhere was that of the perp and not Westerfield? If that was the case Westerfield would not have been arrested.