Updated

The mother of slain teenager Trayvon Martin is telling a National Urban League gathering in Philadelphia to use her story, tragedy and broken heart to stop the same thing from happening to another child.

Sybrina Fulton spoke Friday at the civil rights organization's annual conference. She supports an investigation into whether her son's killer could be charged under federal civil rights laws.

She told the audience that she believes God is using her and her family to make a difference.

A jury acquitted George Zimmerman in the slaying of the unarmed 17-year-old. He was shot and killed during a confrontation with Zimmerman that has spawned a national debate about self-defense laws in Florida and other states.

The National Urban League's conference runs through Saturday at the Pennsylvania Convention Center.