New York -- After years of professing their parents' innocence, the two sons of Julius and Ethel Rosenberg are acknowledging their father was a spy.

The about-face came after their father's co-defendant, Morton Sobell, admitted for the first time that he and Julius Rosenberg stole non-atomic military and industrial secrets for the Soviet Union.

Along with Mr. Sobell and others, the brothers still have doubts about the case against their mother.