Reporting to the government doesn't make you a government agent, doing the search at the direction of the government does.

If a private citizen, on their own initiative, searches your house, finds contraband, and reports it to the government, they may be guilty of a variety of torts and crimes (both civil and criminal trespass, among others, are possibilities), there is no fourth amendment violation.

If a police officer asks them to do it, though, there is a different story.