With a simple Scrubbing.
Neighbors told CBS 11 News that an older couple lives at the home that authorities are focused on. Some believe there was another person living there over the years, but they did not recognize Crusius when shown a picture of him.
https://dfw.cbslocal.com/2019/08/04/el-paso-shooter-identified-21-year-old-patrick-crusius-frisco/