Oscar winner Nicole Kidman called police last week after discovering an intruder had planted an electronic listening device at her $9.5m (€7.2m) mansion in Sydney, Australia.
The Cold Mountain beauty flew back to Australia a day after she was told the unnamed man had bugged the security compound where her guards stay.
Kidman has given footage of the mystery person, caught on her security cameras, to the police who are running tests on the device to ensure they capture the culprit.
Noel McMaster, who runs the actress' security operation, says: "Conclusive evidence has been captured on camera."
A source tells British newspaper The Sun: "Nicole was shocked and she's determined to get to the bottom of it. It came totally out of the blue and really shook her up.
"It was hidden in a security compound where her guards stay and was designed to pick up their conversations."