Craig Castaneda contacted a person advertising online as a mother seeking someone to sexually abuse her nine-year-old child. He traveled from California toward Atlanta, where the person was actually an undercover law-enforcement agent, and was convicted of attempted enticement and interstate travel with intent to engage in unlawful sexual activity. The Eleventh Circuit affirmed his convictions and 35-year sentence. It held that private individuals who discovered child pornography on computers Castaneda left in his condominium were not government agents, so the Fourth Amendment did not govern their search or voluntary delivery of the computers. Their firsthand account supplied probable cause for the warrant. The court also held that Castaneda could not invoke the Fifth Amendment to avoid cross-examination about child pornography after testifying that his online communications were fantasy and that he traveled to rescue a child. The district court properly excluded generalized expert testimony about online role-playing because it would not assist the jury. The sentence, within the guideline range and supported by the conduct and record, was not substantively unreasonable.