Sydney's dad, Jack, was a CIA double agent working against SD-6 on this Jennifer Garner show
Episode Guide: ALIAS: Almost Thirty Years (A22/122) [PAR] Aug 9, 2003 ... Jennifer Garner as Sydney Bristow ... it's Syd (Jennifer Garner) and her father 
going against both SD-6 ... Jack says as long as there is a mole in the CIA, she 
can't tell ... Back at SD-6, Dixon asks Marshall what Sydney's code name was on 
... neck: "You told him that my daughter is a double agent with SD-6.