How did a knife used in deadly stabbing get on Maryvale HS campus?

There are unanswered questions about how a pocketknife got onto the Maryvale High School campus and was used in the stabbing death of a student. Investigators said Chris Aguilar used the 4-inch knife on Tuesday to stab his classmate because he had stolen Aguilar's gun a day earlier. The high school has a weapons detection system that is designed to pick up everything from small knives to high-caliber guns. Alexis Dominguez has more. https://azfamily.tv/45ACQqE #maryvale #arizona #phoenix #news #crime For more Local News from KPHO: https://www.azfamily.com/ For more YouTube Content:    / @azfamily