When tour guides tell the story of Alcatraz, there’s always an asterisk—yes, the prison was totally inescapable except that maybe, possibly, on June 11, 1962, three men made it to shore. On that night, Frank Lee Morris and brothers Clarence and John William Anglin tunneled out of their cells where they left dummy heads sticking out of their beds. They then entered San Francisco Bay on a boat fashioned out of raincoats with homemade paddles. The official story is that they drowned in the Bay, but there has never been confirmation that they did not make it ashore.

Now, researchers from the University of Delft are monitoring a fleet of coconuts they released from Alcatraz to determine if it’s plausible that the men made if off "The Rock," reports Eric Mack at CNET. The experiment is part of a multi-year project conducted by engineers Rolf Hut and Olivier Hoes.

Terrence McCoy at The Washington Post reports that back in 2014 Hut was applying a computer model he designed to simulate the movement of particles and trash to San Francisco Bay. He remembered watching an episode of the television show MythBusters that recreated the Alcatraz escape, deeming it plausible. Hut realized that his model could be modified to look into the escape attempt as well.

So he created a simulation of the tides and currents in the Bay that night in 1962, finding that the trio could have made it to shore, but only if they got the timing right. Using the simulation, they released virtual boats every half hour between 8 P.M. and 4 A.M. from various launching points on the island. They discovered that if they departed between 11 P.M. and midnight and paddled hard, they had a chance of making it to the north end of the Golden Gate Bridge, the spot where the Mythbusters crew landed. But earlier than that and the current would have swept them under the bridge into the open ocean. Later than that, they would have been swept into the Bay, likely dying of hypothermia.

In the new study, Hut and Hoes released coconuts outfitted with GPS trackers and flashing LED lights from a boat near Alcatraz on the night of April 12, which paralleled the tidal conditions of June 11, 1962. Releasing the coconuts at various intervals, they gathered data that they hope will help them refine their original model. The results will be unveiled on a new series called Vanished on the Science Channel later this year.

Of course, the convicts might not have had to rely solely on a boat made of raincoats. Dan Noyes at ABC reports that there was an eyewitness account that says the escapees may have been picked up by a white boat sitting in the Bay off of Alcatraz that night. The CBC reports that family of the Anglin brothers also allege that the men made it out and ended up in Brazil.