Respectfully snipped.
Yes, it is possible depending on the size of the gravel. Screenings and pea gravel, Yes. Railroad ballast, No.
Now
@swedeheart , you are giving away my trade secrets.

An absence of tracks in what should be an active area is a clue in itself. Could LE have missed it? Good chance. Forensics teams are trained to document tracks and sometimes it does not occur to them to wonder why there are no tracks. If I am tracking in the field and the subjects prints suddenly stop and there are no changes of direction, I look closely at the clear area past the end of the track trail. Are there animal prints, insect prints and other natural sign? If not, the subject wiped their trail and I need to get beyond that area to pick up the trail again. With few exceptions, the print trail starts again somewhere past the wiped area. If the clear area contains natural sign, but no trace of the subject, something else happened such as going off trail to one side or another, going up a tree or those pesky alien abductions...