Michael Jackson's maid acted suspiciously during a raid at the star's ranch last year, a sheriff's deputy told a pre-trial court hearing.
Mr Jackson was in Las Vegas when his Neverland ranch was searched
Santa Barbara County Sheriff's Sergeant Ross Ruth said the unnamed maid gave
"evasive answers" when he questioned her during the Neverland ranch raid.
Mr Jackson's lawyers said the November 2003 search was performed illegally.
The 46-year-old singer is expected to attend a court hearing on Friday. He denies 10 child molestation charges.
Officers questioned the maid during their search, while Mr Jackson was in Las Vegas.
"Sometimes she was saying truths, sometimes she wasn't," Sgt Ruth told the court. He became suspicious when the maid turned a light on and off.
Sgt Ruth said he wondered if that was a signal to others in the complex, or whether the switch could have activated an alarm.
The woman was neither arrested nor charged with a crime.
The mother of the boy accusing Mr Jackson of abuse must attend court
The court watched a video of the police raid on Neverland, which showed investigators entering a library stocked with films.
At another point, they entered a museum filled with costumed mannequins - one dressed as Marilyn Monroe.
The tape also showed Mr Jackson's maid escorting investigators into the singer's office.
Defence lawyers said police did not have permission to search the office, but prosecutors said the search had been appropriate.
The mother of the boy accusing Mr Jackson of sexual abuse has been ordered to attend court on Friday to enable the pop star's lawyers to question her.