The mystery of three prisoners who famously escaped from the Alcatraz maximum security jail in San Francisco Bay may have finally been solved, thanks to Big Data and computer modelling.

In 1962, convicted bank robber Frank Morris, together with brothers Clarence and John Anglin, broke out of the infamously “escape proof” facility on Alcatraz Island and attempted to make the treacherous crossing in a raft made from waterproof rain coats. The prisoners were never seen again.

The daring escape plan, which was later immortalized in the 1979 film Escape From Alcatraz starring Clint Eastwood as Morris, saw the convicts spend months digging holes through the walls of their concrete cells. The trio also fashioned dummies and fake heads to leave in their beds, so it appeared to guards as if they were sleeping.

It’s believed the convicts broke out of the prison sometime between 22.00 and 02.00 on June 11, 1962, although investigators can’t be sure of the exact time. However, the timing of their departure from the island would have been critical to their chances of survival, claims a new study by Dutch researchers at Delft University.

Using hi-tech computers and algorithms, the researchers have recreated the trio’s escape attempt.

Dr Rolf Hut, who led the study, told the BBC: “My colleague, Olivier Hoes, was working on a hydraulic model, called 3Di, which is a collaboration between different Dutch companies, agencies and universities.”

“It is a high-performance hydraulic model for simulating the movement of water bodies in deltas and bays. He was using that to simulate the movement of water in the San Francisco Bay area, and I thought we could try to re-analyse what happened back in 1962,” he explained.

The simulations show that if the escapees set off between 23.30 and midnight, when the tide was changing, they might have made it to land. However, if they departed outside of this window, it’s unlikely they would have survived, due to the strong currents between Alcatraz and the coast.

“We didn’t know exactly when the inmates launched their boats, or their precise starting point, and so we decided to release 50 ‘boats’ every 30 minutes between 20.00 and 04.00 from a range of possible escape spots at Alcatraz to see where they would end up,” explained Fredor Baart, a hydraulic engineer at Deltares. “We added a paddling effect to the ‘boats’, as we assumed the prisoners would paddle as they got closer to land.”

But although there was a small window of opportunity, it seems the odds were heavily stacked against the escapees.

“The simulations show that if the prisoners had left before 23.00, they would have had absolutely no chance of surviving,” said Bart, noting they would have been swept straight out into the ocean.

And had the trio left after midnight, it’s unlikely they would have fared much better. Instead of being swept out to sea, the escapees would have been pushed back into the bay, and the model demonstrates they would have spent so long in the water they would almost certainly die from hypothermia.

Here’s a simulation of the worst-case scenario, supposing the prisoners left before 23.00:

photo credit: REMY SAGLIER – DOUBLERAY via photopin cc