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MIAMI (CBSMiami) – The National Transportation Safety Board says they still have a lot of work to do before they can even begin to assign blame for the deadly pedestrian bridge collapse at FIU.

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Miami-Dade County’s top prosecutor Katherine Fernandez Rundle says her office is focused on helping the appropriate agencies figure out the cause and preventing it from every happening again.

More interestingly, Rundle says criminal charges are “improbable.”

This despite the fact that witnesses have yet to be interviewed and the NTSB has said that its investigation is in the very early stages.

“We are really a background, we’re not forefront,” she said. “We are not going to be the ones making a determination as to the cause of the collapse. We want to be there for the families, we want to be there for the community, we want to be there for law enforcement.”

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She says prosecutors will likely only step in on a criminal level after the investigation has concluded and if someone is found negligent.

“In the criminal arena, it’s a very narrow scope, what was the cause of death and what was the manner, so we won’t know that until NTSB tells us what caused that collapse that resulted in these deaths,” Rundle said. “The only cases, they are very challenging, they are super complex, they are very difficult to fit into a criminal container if you like. The criminal law is very refine and very restricted and very high bar, so the challenges are immense.”

Gallery: Scene of the FIU Bridge Collapse 

The pedestrian bridge was an FIU project, which means the university and its contractors are responsible for reviewing plans, permits and inspections.

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The university says it followed all processes and procedures.