Based on the pictures just linked by Nurse with the crime scene truck being near her residence, I think whatever happened - it occurred there. The perp then cleaned up or whatever, perhaps stayed thinking about what to do, and decided to go up to that parking lot early in the morning so as not to leave the baby alone in the running car for too long. That person left the baby in the car with the hazards on to attract attention. I think driving that far to such a remote area, the perp thought it would divert attention away from him or herself.
I think a neighbor reported seeing the perp's car in her driveway/parking area, and that's where the info from the other car came from.
This scenario leads me to believe that it was someone who cared about the child.
ETA: I think the second car was used to transport Krista and hence the reports about physical evidence being retrieved from that vehicle. Also, I think the perp, by setting her car up the way s/he did, wanted to make everyone think that Krista abandoned her little girl due to stress or whatever.
