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.
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