I think therein lies the problem... It wasn't sophisticated. It was a slipshod investigation job from the get-go.
Someone that's going to break into a house to kidnap a 5 year-old... They're going to have a history of doing that. And they're going to do it again. On top of that trying to kidnap a kid from an affluent home, with all the bells & whistles an affluent home would have? No, only an idiot would do that and an idiot would get caught at some point.
This was an inside job.
Read a book on the Martha Moxley murder... Similar type of investigation. You take a police dept that's not use to investigating a real homicide and all hell breaks loose and proper procedure goes out the door.