Bank robbers John and Clarence Anglin made multiple escape attempts from lesser prisons after their 1958 conviction. So they were sent to the ultimate lockup of the day: Alcatraz.

On June 11, 1962, the brothers escaped with another man. Did they drown or are they still on the run today?

This summer for the 50th anniversary of their escape, Marie Anglin Widner -- sister to Clarence and John -- along with her sons are planning a trip to San Francisco to visit the famed prison, where they will honor their escapee kin, NBC/ABC station WALB of Albany, Ga., reported on its website.

 John and Clarence Anglin robbed a bank in Columbia, Ala., with toy guns in 1958. A few days later, they were captured in Cincinnati and sentenced to long prison terms. Their escape attempts eventually landed them at Alcatraz.

"The only reason they put them in Alcatraz was because they could not keep them anywhere else they put them," Widner, of Lee County, Ga., told WALB. "They kept getting away."

At Alcatraz, the brothers met Frank Morris, the mastermind of the operation, which involved elaborate digging and handcrafted dummies and life rafts. Authorities believed the men probably drowned in the cold, turbulent waters around Alcatraz.

But not Widner, who told WALB that her brothers did not die during the escape. "We know they are OK," she said.

If the brothers survived the swim, they would be the only people to successfully escape The Rock. They would be in their 80s today.

Widner's sons David and Ken recall FBI visits to the house and bugged phone lines. They told WALB that the feds stopped by just months ago.

The family is hoping to persuade the government to return some of the brothers' items.

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 This article includes reporting from NBCBayArea.com and msnbc.com staff.