It seems plausible, with all the missing footage and the hour it took for her car to get to the front gate, that the ex could have went after her before she reached the gate, they argued or whatever and he killed her. Since they have not searched the boys house or his surrounding property which is huge by the way, could it be that he dumped her body somewhere on that land before proceeding to take her car, leave the gated community that hour later and drive it down to malibu to divert attention away from him?