During interrogations, the former agency official said, officers worked in teams, watching each other behind two-way mirrors.

NEWYORKER: The Black Sites

Back then, it was known as Mulholland Farm and had a casino, secret passageways, two-way mirrors and peepholes.

WSJ: On Former Errol Flynn Estate, a House for $7.9 Million��WSJ Private Properties

Counseling rooms are equipped with two-way mirrors so parents can observe sessions.

FORBES: Wired