WATERLOO, Iowa (AP) — More than 200 people filled an amphitheater in Waterloo to draw attention to missing persons cases and demand justice for the slain. The Waterloo-Cedar Falls Courier reports that Wednesday’s vigil was organized by the Family and Children’s Council of Black Hawk County. It aimed to bring awareness to missing and unsolved crimes involving young people.

Heather Collins is the mother of 8-year-old Elizabeth Collins, who disappeared with her cousin Lyric Cook Morrissey in July 2012. The girls were later found dead. Collins says she’s alarmed by the number of youths reported missing.

To assist with the growing number, Democratic Sen. Jeff Danielson spoke about pursuing a state Amber Alert-type system that could provide immediate notification through social media and other channels. He says the system wouldn’t have the same rigid criteria required for an Amber Alert.