ARI SHAPIRO, HOST:
When San Francisco's Alcatraz prison was completed in 1934, it was believed to be impenetrable.
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UNIDENTIFIED PERSON #1: (Unintelligible).
SHAPIRO: That is until three inmates, Frank Morris and brothers John and Clarence Anglin escaped in 1962.
AUDIE CORNISH, HOST:
How? The trio made fake heads out of materials from around the prison - soap, concrete dust, bedsheets, even human hair. They planted the decoys in their beds to fool the guards while they dug a hole through the wall at night. The whole process took months until one night they finally went for it.
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UNIDENTIFIED PERSON #2: Three bank robbers serving long terms scratched their way through grills covering an air vent, climbed a drainage pipe and disappeared from the forbidding rock in San Francisco Bay.
SHAPIRO: Once they escaped, they were never seen again. Those fake heads are still around, though. They're considered evidence in the ongoing open case to find the escapees. As you might imagine, they're deteriorating.
CORNISH: So the FBI was asked to create replicas. And after months, they completed them this week.
SHAPIRO: A 3D printer did a lot of the work, but they did keep some of the same materials.
PAULA ERNST: We obtained hair from a hair dresser just like the escapees did back in the day. But we dyed them to match the color of the hair and then glued them in sections onto the 3D-printed heads.
CORNISH: That's Paula Ernst with the FBI. She oversaw the project. One thing that surprised her about the original heads was how big they were.
ERNST: I'd say they're about 25 to 30 percent larger than human head.
JOHN MARTINI: You know, once you commit to a certain size, you kind of got to either stay with it or throw the whole thing away and start over again. So they may have, like, laid out the head and gone, large - well, what the heck? You know, who's going to notice?
SHAPIRO: Alcatraz historian John Martini says the size probably didn't matter.
MARTINI: The guards just expected to see heads in those beds. They didn't have to be, you know, perfectly lifelike to pass a quick inspection of a guard walking by at 3 a.m., you know, just on his routine patrol.
SHAPIRO: The new heads will be on display at the prison for visitors. The old heads have been safely tucked away.
CORNISH: And while they all could eventually be used in a trial, Martini doesn't think they ever will be. In his mind, the case is settled.
MARTINI: I don't think this is going to do anything more towards solving the case except maybe bring up more red herring theories of what happened to these guys. The most likely explanation is the simplest one, and that's that they're dead.
(SOUNDBITE OF SONG, "JAILBREAK")
THIN LIZZY: (Singing) Tonight there's going to be a jailbreak somewhere in this town. See; me and the boys - we don't like it, so we're getting up and going down. Hiding low, looking right to left... Transcript provided by NPR, Copyright NPR.