This clip from the BBC about Peaches Geldof's funeral, ends by saying, “Her cause of death remains unexplained.”
No cause can be “unexplained”. It is the death which is “unexplained”. The “cause” is unknown. An unexplained cause is one which you know, but which you do not understand. That is not the case in this instance.
What help is there for civilised society if the BBC cannot use English properly?