Colleagues Say C.I.A. Analyst Played by Rules

By DAVID S. CLOUD

Published: April 23, 2006

WASHINGTON, April 22 — Mary O. McCarthy, the intelligence officer dismissed on Friday after being accused of leaking information to reporters about the Central Intelligence Agency's overseas prisons, once was responsible for guarding some of the nation's most sensitive secrets.

As a senior National Security Council aide for intelligence from 1996 to 2001, Ms. McCarthy was known as a low-key professional who paid special attention to preventing White House leaks of classified information and covert operations, several current and former government officials said.