Trayvon Martin's mom says law let Zimmerman off the hook

(CNN) -- Florida law kept George Zimmerman from being held accountable in last year's shooting death of Florida teenager Trayvon Martin, the teen's mom said Friday.

"Wrap your mind around no prom for Trayvon, no high school graduation for Trayvon ... all because of a law -- a law that has prevented the person who shot and killed my son from paying for this awful crime," Sybrina Fulton said Friday afternoon at the National Urban League Conference in Philadelphia.

Zimmerman, a former neighborhood watch volunteer, was found not guilty in the 17-year-old Martin's death on July 13.

He fatally shot Martin in the Sanford, Florida, neighborhood where Zimmerman and Martin's father lived in February 2012. Zimmerman, who is Hispanic, had a confrontation with the unarmed African-American teen after calling police to report a suspicious person, and he said he shot Martin in self-defense.

The case became a flashpoint in debates over racial profiling, and thousands attended vigils across the country over the weekend, decrying the verdict.

Fulton asked attendees of the National Urban League gathering Friday to use her "broken heart" to ensure "there are no more Trayvon Martins again."

"My message to you is: Please use my story. Please my use my tragedy. Please use my broken heart to say to yourself, 'We cannot let this happen to anybody else's child,'" she said.