Anyone in the open field who touches someone who has been killed by the sword or has died of natural causes, or anyone who touches a human bone or a grave, will be unclean for seven days.
Jewish Publication Society of America Version (JPS1917) - Numbers 19:16 >And whosoever in the open field toucheth one that is slain with a sword, or one that dieth of himself, or a bone of a man, or a grave, shall be unclean seven days.