Oh, yes you can. If JonBenet were found a park, and the only person known to be in the area was a groundskeeper, the groundskeeper would be assigned added suspicion. If JonBenet were found in a closet in a library, and the only people known to be in the library during the time frame involved were two librarians, both would be assigned added suspicion. A major component of crime investigation is exploring who had control, or felt they had control, over the scene of the crime. The Ramseys had absolute control over the scene of JonBenet's death. They knew how sound traveled, they knew how light fell, they knew where every item involved should or should not belong, and they belonged in the house. Just as with the groundkeeper, or the librarians, they deserve to be suspected because they know more than other people how easy or difficult it would have been to kill JonBenet at the location she was found.
It is a simple fact that if JonBenet was killed by an intruder, the murder was unique in all of history, due to how much square area of house the crime took place over (spanning from the second floor of the house to the basement, and from the west side of the house to the east), and how long JonBenet's murder took. All murders of children inside their own homes, by intruders, have taken place in one room, and have taken mere minutes. All other children killed in their own homes have been killed by their parents, or relatives or family friends known to be in the house.
JonBenet's death was not unique, therefore it should be investigated as what it most likely is (death by parent) rather than what it has never been before (death by intruder with extensive body movement within the house).