Footprints are fairly common at crime scenes
Footwear marks are found at around 40% of crime scenes. In the United Kingdom, there has been a National Footwear Intelligence and Refererence Database established. They report that , Nike shoes are found most often at crimescenes there, with 60% of the shoeprints coming from this manufacturer. The most commonly encountered shoe was the Nike the Air Max 95. The bloody shoe prints at the crime scene of Nicol Simpson and Ron Goldman matched a size 12 Bruno Magli shoe, a relatively rare Italian-made model. O.J.Simpson wears size 12 shoes, which isn't that common a size. The prosecution linked O.J. Simpson to purchases of this type of shoe in order to link him to the murder scene.
More here :
http://www.science.marshall.edu/murraye/Footprint%20Lab.html
UK Forensic Science Service Footware evidence
http://www.forensic.gov.uk/html/services/expert-solutions/footwear/
http://www.usatoday.com/news/index/nns25.htm
http://law2.umkc.edu/faculty/projects/ftrials/simpson/evidence.html
http://www.wagnerandson.com/oj/heel.htm
http://www.wagnerandson.com/oj/fprint.htm
http://www.wagnerandson.com/oj/feet.htm
