I had not seen the narrow tracks in front of the house before. My first thought -- sorry for the graphic visualization -- is that it's about the width of a person, making me wonder if the marks could have been made by the dragging feet of a person?
At the same time, it's hard to imagine that LE wouldn't have seen the tracks immediately and been all over them looking for dropped items or DNA evidence. So maybe the tracks were not there immediately after the crime and instead were made by some LE equipment or the legs of a media tripod?
MOO