A mole hunt - a intelligence agency's search for a suspected enemy within - is a tricky and delicate business, somewhat like a surgeon removing his own appendix.

The great mole hunt, a drama of epic proportions, all but crippled the agency at the height of the cold war.

Instead it focuses on the mole hunt of 1963 to 1974, the most dramatic and controversial years of Angleton's work with the agency.

And so, Mr. Mangold maintains, the mole hunt was born of this folie a deux between two men of a similarly conspiratorial bent.

It was only a matter of time before the mole hunt, hitting fever pitch, would turn on the hunter.

That was at least partly because he had unwittingly stumbled into another mole hunt, this one focused within ranks of the C.I.A., bureau officals said.

Before it was all over, Angleton became a victim of his own mole hunt.

But the two cases were unable to explain the earlier losses, officials said, and the mole hunt continued.

Some promising suspects were cleared, and the mole hunt found other penetrations such as CIA officer Harold James Nicholson.

Mr. Woolsey said Mr. Price had received a mild reprimand for failing to focus on the mole hunt during that period.