Investigation
The next morning police searched for the escapees on Alcatraz and Angel Island without success. An investigation by the Federal Bureau of Investigation was begun as well.
Remnants of the raft, paddles, and a bag containing the Anglins' personal effects were found on Angel Island. According to the FBI, while it was theoretically possible for the three inmates to have reached Angel Island, the cold water temperature and direction of the ocean's tides made this unlikely. The FBI also said that the plans of the inmates were to steal clothes and a car once they reached land, although no car or clothing thefts were reported in the area following the escape. The case was closed by the FBI on December 31, 1979, after a 17-year investigation. It was concluded that the prisoners drowned in the cold waters of the bay while trying to reach the mainland.
As late as September 2009, the case was still being investigated by the U.S. Marshals Service, according to a story broadcast on NPR. Deputy U.S. Marshal Michael Dyke told NPR, "There's an active warrant and the Marshals Service doesn't give up looking for people," he said. "In this case, this would be like saying, 'Well, yeah, they probably are dead. We're going to quit looking.' Well, there's no proof they're dead, so we're not going to quit looking." Dyke said that he still receives leads, including one as recently as two weeks before the story aired.
In the first season of Mythbusters (eighth episode, first aired December 12, 2003) the feasibility of escaping Alcatraz on a makeshift raft was tested and judged to be possible.
According to a 2011 program on the National Geographic Channel, investigators had found footprints leading away from the raft on Angel Island, and had also identified a blue Chevrolet car stolen that night, contrary to the FBI report.
Read more about this topic: June 1962 Alcatraz Escape