In the two-and-a-half-minute video, the teenage boys can be heard yelling, “We’re not going to help you and you never should have gotten in there.”
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There is no Florida law that requires a person to provide emergency assistance.
Prosecutors had considered charging the group with failing to notify a medical examiner of a death, but said they could not appropriately apply it in Dunn's case without new legislation.
At the time the video was taken, the group ranged in age from 14 to 18.
After the incident, a Florida state legislator crafted a good Samaritan bill that would have made it a crime not to assist someone in need, but lawmakers rejected it.
"I know that everyone was sickened by the callous disregard for human life exhibited by these young people. We can only hope that this was an isolated and rare circumstance that will never happen again," State Attorney Phil Archer said.
"Unfortunately, Florida law does not address this behavior and we are ethically restrained from pursuing criminal charges without a reasonable belief of proving a crime beyond and to the exclusion of every reasonable doubt."