In United States v. Miller, 688 F.2d 652 (9th Cir. 1982), the victim of a theft received an anonymous tip that his stolen trailer was on Miller's property.
The victim contacted a federal agent and a sheriff. The sheriff noticed a trailer parked next to the frontage road running to Miller's property with a "for sale" sign on it.
The victim met with the federal agent and the sheriff and offered to go inspect the trailer as a potential buyer. The victim went to Miller's property, identified his trailer, which was one different from the one for sale that was visible from the road, and reported this information back to the federal agent and the sheriff. Id. at 655.
The victim then suggested that he go back to the property to take some pictures. The federal agent followed the victim and positioned himself where he could see but remained off of Miller's property and out of sight. Based on his observations, the federal agent obtained a search warrant for Miller's property. Id. at 655-56.
The Court of Appeals affirmed the trial court's denial of Miller's motion to suppress, holding that the Fourth Amendment was not violated because the victim's conduct was not instigated by the officers, it was not illegal, and the officers remained out of sight and did not cast a "police aura" around the victim's actions. Id. at 657-58.