JACKSONVILLE, Fla -- Years after a threat that was never carried out at Douglas Anderson School of the Arts, Frank Henderson says family is the best defense against a message of violence.

"A lot of times, they're searching for different things," Henderson said.

Investigators say back in 2015, Henderson's granddaughter used the messaging app Kik to threaten people at her school.

They say she even pledged allegiance to ISIS and detailed weapons she had. Police investigated and found the text threats were not serious.

"We sat down and talked and we discussed and found out what was really going on. If you can't be true to your family, you can't be true to yourself," he said Thursday.
On the anniversary of the shooting at Columbine High School in Colorado, many students across the country made threats not knowing the lasting impact.
For example, Henderson's granddaughters still has pages of articles online listing her names and the crimes she's accused of.
Still, Henderson says he's not worried about her future.
"She made a mistake and we wrapped our arms around her," he said. "She's an honor role student now and she's going on, the sky's the limit for her now."
Henderson only agreed to speak out years later because he wants to encourage families to talk and perhaps that he says will prevent the worst of possibilities.
"You can have down times in your life," he said, "but see, this is what families do. We pull each other up when need be."