Despite maintaining his innocence for more than 50 years, a tried and convicted Commie spy has finally confessed his guilt at age 91!

In 1951, Martin Sobell was arrested along with Julius and Ethel Rosenberg on charges of espionage.  The trio was charged with selling US atomic secrets to then USSR.

Sobell served more than 18 years on The Rock – Alcatraz- and other federal pens and after his release in 1969 became a progressive cause advocate.

Now, Sobell, 91 told The New York Times that he was indeed a Soviet spy and so was co-defendant Julius Rosenberg who he implicated in a conspiracy to deliver to the Soviets highly classified military and industrial secrets in the manufacture of atomic weaponry.

Historians have long speculated on the involvement of Rosenberg’s wife – Ethel – spy or not?

"She knew what he was doing but what was she guilty of?" Sobell said. "Of being Julius’s wife."

After President Dwight D. Eisenhower denied a clemency plea, The Rosenbergs were executed in the electric chair at Sing Sing in 1953.

Sobell claimed what he leaked to the Soviets was nothing but low level documents not key atomic secrets.

"What I did was simply defensive, an aircraft gun," he said. "This was defensive."

One device, according to The Times, was the SCR 584 radar, believed by military experts to have been deployed against American airmen in both Korea and Vietnam.

Thanks a lot, Marty.

(pictured: Julius Rosenberg)