Of course it is possible to park on the cul de sac and not be seen but what a chance you are taking..
There is a huge home that has an eagle's eye view to the home and property. How would anyone know when people leave for work, esp. a contractor who has odd hours. There are people coming and going all the time from that property. It would take a large amount of luck and a brazen motivated perp to pull this off w/o a hitch.
Sierra leaves the house. Carrying a bag in one hand, books in the other, has to maneuver keys, a cell phone( I bet she carries it in her hand), deadlock her door. She had to put something down, I suppose. If anyone approached her, or tazed her, she would most likely scream. She is feisty and could run faster than that car could go in that circular driveway. She could have screamed at the second gate and alerted. The perp had to have all the stars aligned at that hour. One neighbor goes out each morning to get his newspaper too.
I just don't get this. Either the dogs are wrong and she was forced into a vehicle on the road or she knew the perp. I will always leave wiggle room for the crazy psychotic offender but the secreted bag practically washed that all away.
In the last thread, someone posted about the outbuilding off to the side of the house. It has a new roof, which is evidenced if you compare the Google and Bing view of the property. And later someone posted that they thought the Google image (old roofing) was from October 31, 2011. Nothing shows for image date on the Bing view--the one that shows the new roof.
Sierra moved into that home in October 2011, right?
And it appears from the bird's eye views of each map that the roof was in need of replacement in the Google view from October 31, 2011. So that might mean that roof was replaced after that date, or, after Sierra was living in that home. I do believe roofers might have a view of the LaMar home.
Certainly I am not accusing anyone in particular, but I am curious about when that roof was replaced and by whom. One or two workers could do the task, but sometimes such work is done by a crew. And whether it was a lone roofer or a crew, they might have taken several days to do the job. In that time, any one of them could have locked onto Sierra and been smitten, having seen her coming and going from the house. And if we were able to find a bus route/schedule information, so could they, IMO, which would give them info on what time she leaves the house. A determined perp could have watched over time and seen a pattern to when the adults left each day, as well.
A car could have been parked near that building that morning and no one noticed. And someone mentioned the layout of the house being such that there are hiding places around the house itself...not for a car but for a person to lurk and wait.
Maybe this is a longshot. But worth checking out by LE, IMO.