The shooter who killed three UNLV faculty members Wednesday mailed at least 22 envelopes without a return address to education professionals across the country before entering the campus with a Taurus handgun and 11 magazines of ammunition, Clark County Sheriff Kevin McMahill revealed at a news conference Thursday afternoon. One envelope contained a white powdery substance that is being analyzed by police The Clark County Coroner identified two of three UNLV faculty members killed during Wednesday’s on campus shooting. Las Vegan Patricia Navarro Velez, 39, was an associate accounting professor…