Footprints and impressions. Random facts

I said in an earlier post that there wasn't a database for every shoe in the country, this is true, but i found out that the fbi does work with some shoe manufactuers to get a pretty good database of different brands and types of shoes. Everyones stride is different and it shows in how your shoes wear down; some walk mostly on the back of their shoes and some more on the sides, and if you're a runner they may be on the balls of the feet. Stride or longitudal distance from foot to foot can tell height, and the lateral distance can tell weight, because a long narrow stride wouldn't belong to a short fat man. This stuff paints a picture. Footprints can also make a trail to where items were stashed like gloves or weapons. If the same footprints show up in multiple crime scences then the crimes may be linked. If there are 3 different sets of prints then there were 3 people involved in the crime. Investigator's prints are also taken as a precaution, but they may wear surgical booties or walk on coasters to prevent excess prints. A few methods to avoid surface erosion where making casts of a print are practical too. Spraying hairspray on sand keeps the shape, blowing mud dry with a hair dryer, and using snow wax makes the surfaces retain shape. There is also a method for carpet that i can't remember.