A crane that was on the construction site before the Florida International University pedestrian bridge collapsed in March was driven away from the scene shortly after the span crumbled down killing six people.

The white crane, rented from a Sweetwater firm called George's Crane, was still at the scene in the moments after the horrific 'instant bridge' crashed down onto the roadway, according to the Miami Herald.

One person in particular noticed the crane drive away from the deadly scene- a homeless man named Carl Robertson, 73.

Robertson who lives in the area where the bridge used to stand, and was the first person to call 911 using his old cell phone, says the crane operator 'drove away... and nobody stopped him.'

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Mystery: Why did the crane's operator from George's Crane decided to drive the massive machine off the site of the bridge collapse at Florida International University that killed six people in March

The massive white crane (circled) was driven for 30 blocks and parked back at George's Crane lot shortly after the 'instant bridge' collapsed

Moments after the bridge collapsed the crane was still at the scene (pictured on right)

However, in this image the crane, which should still be on the left side of this image, has disappeared

Despite being one of the eyewitnesses to the scene that fateful day, police never took a formal account from Robertson.

He says it wasn't until later that day that he started to think about the white crane and the behavior of its operator, 'I didn't have my wits about me because they were pulling people out.'

However, as he processed the traumatic event he had witnessed, he realized something felt off about watching this large machine being driven away.

Robertson says he witnessed the bridge collapse, then, he claims minutes later, the crane's operator jumped from his cab and untied the caution tape that police had just anchored to his machine.

Then he fired up the rig and left, driving west down Tamiami.

According to a lawyer for the crane company, the driver was simply moving the machine out of the way for the first responders rushing to aid people trapped and injured.

Bryant Blevins, the attorney for George's Crane explains that the 'emergency vehicles needed access. They were getting there pretty quickly after the collapse. At that point, he had to move the crane.'

While not a lot of information is publicly available about the collapse, during the investigation into the incident by the National Transportation Safety Board, police clarify they do not believe that the crane's operator fled the scene.

Carl Roberstson, a homeless man who lives near where the bridge was being constructed and was the first to call 911 on his old cell phone, says he found it odd to see the machine being driven off the site following the collapse

Local law enforcement with the Miami-Dade Police Department say the operator stuck around long enough to offer help, but it is unclear for just how long.

At some point soon after the collapse, the operator drove the crane off the site, for about 30 blocks, to George's Crane lot in Sweetwater.

While that is where the crane stayed, the operator later returned to the scene that evening where he was interviewed by police and one of the federal agencies, the Occupational Safety and Health Administration (OSHA), that is also investigating, according to Blevins.

An attorney for the family of Alexa Duran, an FIU student who was killed, says he is angry a piece of equipment was removed from the site of the collapse.

'Why would he leave the scene?' asks the Duran family attorney, Alan Goldfarb. 'It doesn't make any sense. ... How could you remove equipment from an investigative scene?'

The horrific collapse killed six people and the Miami-Dade Police are investigating the deaths as homicides

Meanwhile, the Miami-Dade Police Department is investigating the deaths as homicides.

They say they have an idea of why the crane left, and that they don't believe the operator has anything to do with the collapse.

Capt. Alex Acosta tells the Herald 'He moved it right there on site, off to the side,' adding, 'He must have just got nervous.'

Acosta adds that while operator, who has not been publicly identified, first offered help, he then left the scene, dropped the crane off at George's Crane lot, and returned home.

Police later figured out who he was and called him back to the scene.

'He came back voluntarily and was interviewed,' Acosta said, adding that no action was taken against him.