SAN FRANCISCO – Half a century after a notorious prison escape from Alcatraz Island, the FBI has created replicas of decoy heads that inmates used to distract guards from a plan that still captivates researchers and tourists.

Authorities recently unveiled 3D-printed copies of the decoys that inmates Frank Morris and John and Clarence Anglin constructed with soap, plaster and human hair.

Morris and the Anglin brothers placed the decoys in their beds and climbed through a wall to escape the island prison in San Francisco Bay. The men were never found.

Inmate Clayton West also created a head but never made it out of the maximum-security prison that housed dangerous criminals such as Al Capone and offenders with a history of escaping.

Authorities said they made the replicas to share with the public because the original decoys are fragile and are evidence in the still-open investigation into the escape by the U.S. Marshals Service.

“We understand the original items can’t be out here – they’ve got to be archived,” said John F. Bennett, FBI special agent in charge in San Francisco. “But we recognize that those items are also part of the rich and historic fabric and the landmark of this city.”

“The hair and the paint on here is exactly what the prisoners did,” Bennett said, showing the replicas brought to the island in black, waterproof cases.

The FBI investigated the prison break – which was featured in the 1979 movie “Escape from Alcatraz” starring Clint Eastwood – for 17 years before it was turned over to the Marshals Service.

Now, Alcatraz visitors can see models of the heads on display that were used in the movie. The FBI hopes the public will soon be able to view the agency’s replicas, which were unveiled to some media outlets along with “Wanted” signs for the long-escaped inmates.

Authorities are investigating any and all credible leads, said Don O’Keefe, U.S. marshal for the Northern District of California.

“Some may believe that we’re chasing shadows, but our efforts are meant not just to perform due diligence, but to be a warning to other fugitives, that U.S. Marshals don’t give up because of the passing of time,” he said in a statement.