http://en.wikipedia.org/wiki/Aldrich_AmesAldrich Ames
Aldrich Hazen Ames (born May 26, 1941) is a former Central Intelligence Agency counter-intelligence officer and analyst, who, in 1994, was convicted of spying for the Soviet Union and later Russia.
As early as 1985, the CIA's network of Soviet-bloc agents began disappearing at an alarming rate. The CIA noticed that something was very wrong, but was reluctant to admit that there was a mole in the agency. Initial investigations were far more focused on a communications breach caused by Soviet bugs or by a broken code. By 1990, the CIA was certain that there was a mole, but could not find the source. Recruitment of new Soviet agents came almost to a halt.
The CIA was harshly criticized for not focusing on Ames sooner, given the dramatic increase in his standard of living. One of Ames's co-workers (also a friend of his wife) noted that Mrs Ames was able to make payment in full for drapes in their house, even though that co-worker (in similar circumstances) was obliged to pay in installments. Despite Ames's official salary of $60,000 USD he was able to afford
A $540,000 house in Arlington, Virginia, paid for in cash;
A $60,000 Jaguar car;
Monthly phone bills exceeding $6,000, mostly calls by Ames's wife to her family in Bogotá, Colombia;
Tailored suits replacing Ames's former 'bargain basement' clothes, conspicuously better than those of his CIA colleagues;
A superior credit score — Ames maintained premium credit cards whose minimum monthly payment exceeded his monthly salary.