What the prison found
At the morning check on June 12, 1962, guards at Alcatraz found Frank Morris and brothers John and Clarence Anglin missing from their cells. The men had left dummy heads in their beds. A fourth inmate, Allen West, helped plan the escape but did not leave with them. The prison went into lockdown and a search began.
The physical evidence inside the prison is one reason the FBI can tell the first part of the story in detail. The men had made openings in their cells and prepared equipment for leaving the island. What was left behind could help reconstruct the plan and the route out of the cell block. It could tell investigators far less about the men once they were on the water.
The bay creates a gap in the record
The FBI’s account describes recovered materials associated with the attempt and a search that never located the men. An item recovered in the bay can show where the item traveled. Whether it moved with the men, separated from them during the crossing or drifted afterward is a different question.
A persuasive account of survival needs evidence that places one of the escapees alive beyond the crossing. A persuasive account of death needs evidence that resolves what happened to the men themselves. The conditions on the bay give context for assessing either possibility, but the missing evidence still matters.
How to read later claims
A reported sighting, a family recollection or a disputed image can be a starting point for research. Ask whether the record is contemporaneous, whether the person can be identified and whether another source independently confirms the location. Check those things before placing it on a timeline as fact.
The FBI’s historical account separates the physical evidence and the search from what it could determine about the men’s fate. That separation explains why the case can be remarkably detailed about the escape itself and still leave its most famous question unanswered.