It seems to me that this jibes almost perfectly with your theory that there is more to this case than meets the eye. From all the reports we've seen [Danielle's blood in Westerfield's motor home, child porn on Westerfield's computer, Westerfield's inability to account for his whereabouts beginning at exactly the time - 9:30AM Friday morning - that the Van Dams discovered Danielle missing], the SDPD and the DA have more than enough evidence to nail Westerfield. The only possible reason these detectives would want to re-interview Westerfield is that they don't believe he's the perp - or that they suspect that he was not working alone.