its still an open question.
the medical examiner has never been able to specifically determine which was the cause of death, citing BOTH the blow and strangulation. right on page 1 of the autopsy report, both asphyxia and cerebral trauma are cited. they don't know which came first, both things COULD have killed her by themselves, they are not sure which one did.
There is also evidence, per the autopsy report , of petechial hemorrhaging around the face and neck as well. This also is indicative of death by strangulation. The blow to the head was a coup des gras and indicates to me at least that this was his first kill and he wanted to make sure she was dead. But, she was already dead.
The most important recent exidence to come to light was that given by the M.E. from Phoenix regarding the paintbrush. Perhaps you'd like to answer the question, " Who raped Jonbenet with the paintbrush, Mommy or Daddy and why do you think they felt this was necessary?"