The most recent documentary I saw indicated that the physical evidence has been re-tested, and based on more advanced methods than were available at the time of the crime, the DNA is indicating the killer was a Hispanic male.
Also in the documentary was an interview with Patsy Ramsey who said that they were part of a Christmas Open House tour that year, and she was bemoaning the thought that the killer could have been someone who had just toured the house. In a later interview with the father, he said the broken basement window made him think that the killer broke in while the family was out earlier, then stayed hidden in the basement while they returned and until they all fell asleep.
I do agree the ransom note and the father's being heard saying "we are not addressing you" to his son who was interrupting him were both odd. But DNA evidence has ruled out the immediate family. But really a tragedy all the way around.