The authorities in California have found wireless microphones around the sheriff's department office where Michael Jackson was interrogated.
Michael Jackson denies any wrongdoing
Police say they believe someone in the media was trying to bug investigators on the day the pop singer handed himself in for questioning.
Michael Jackson is due to appear in court in January faced with multiple child sex abuse charges.
The pop singer, who has been released on $3m bail, denies all the charges.
According to a spokesman for the Santa Barbara Sheriff's Department, several wireless microphones were discovered close to where officers take their breaks. It is an outside area that is not easily accessible to the general public.
The microphones apparently disappeared a few hours after they were spotted on 20 November - the day Michael Jackson surrendered to police.
There was a huge media presence at the building and the spokesman acknowledged the microphones might have been left behind accidentally but he said that was highly unlikely.
It is not known who was responsible for removing them.
The police say they suspect it was an attempt by somebody within the media to gather information by listening to discussions between police personnel.
Officers in Santa Barbara say they will be on their guard against future attempts to spy on them.
Brother flees cameras
Meanwhile, the media frenzy over the case reached the corridors of the United Nations in New York as Jermaine Jackson fled from camera crews after refusing to answer questions about his brother.
More than a dozen crews turned up to film Jermaine Jackson, who was promoting a World Aids Day boxing and musical event to be held in Nigeria in January.
But questions about his younger brother were cut off by a moderator and Jermaine Jackson was whisked away by his handlers.
Reuters news agency said that Jackson sprinted down a corridor outside the UN Security Council chamber with TV crews in hot pursuit, yelling questions at his back.